What is the biggest killer of startups? (And How to Prevent It)

If you spend any time on Twitter, LinkedIn, or YouTube, it can look like building a startup is quick, clean, and always “up and to the right.”

Reality is very different.

Building a startup is hard. Building a startup alone is exponentially harder.

After more than 20 years in startups, Rob Walling has seen a clear pattern. The founders who burn out, waste money, and spend months building the wrong thing are almost always the ones trying to do it all by themselves.

In this post, we will answer a key question many founders ask: What is the biggest killer of startups? For a lot of early founders, it is not funding, code, or ideas. It is isolation.

You will learn:

• Why building alone slows you down and wears you out
• Why you do not need a co-founder, but you do need peers
• How mastermind groups work and why they are so powerful
• Simple steps to find or join a group that fits your stage

Let us start with the danger that hides in plain sight.

Why Building Alone Is the Silent Killer for Founders

Founders love to say they “wear many hats.” That sounds heroic. It also hides a problem.

When you build in isolation, you:

• Move slower than you should
• Make decisions in a vacuum
• Carry the whole emotional load by yourself

This is where a lot of startups quietly die. The product might look fine. The market might be there. The founder is the one who runs out of energy, focus, or hope.

Common solo traps include:

• Solving problems that others have already solved, instead of asking for help
• Losing sleep over choices that a peer could gut check in ten minutes
• Spending months on a feature that another founder could tell you is not needed
• Feeling stuck, but not having anyone you trust to talk it through with

When you are alone with your thoughts, every problem feels huge. Every choice feels final. That constant pressure is a silent killer.

To see why, it helps to break it into three main risks.

The Echo Chamber Trap: Moving Slower Than You Should

When you build alone, you live inside your own head. Ideas bounce around, but nothing pushes back.

You end up:

• Reinventing tools and systems that already exist
• Solving technical or business problems from scratch
• Missing easy shortcuts that other founders use every day

Imagine spending three weeks building a custom billing flow, only to find out later that everyone at your stage just uses a simple off-the-shelf tool.

A single 20-minute chat with another founder could save you those three weeks.

Some signs you are stuck in your own echo chamber:

• You keep “researching” the same problem without making a call
• You are not sure what “good enough” looks like, so you never ship
• You keep second-guessing decisions because you never test them with anyone

When you can talk with founders who know your space, you move faster. They can say, “Yeah, we tried that, it did not matter,” or, “You are overbuilding that part, ship the simple version first.”

Speed comes from feedback, not just effort.

Analysis Paralysis: Endless Debates Without a Sounding Board

Another quiet killer is overthinking. When you do not have anyone to bounce ideas off, every path feels risky.

The loop looks like this:

1. You sit alone and list out all the options in your head.
2. You try to weigh every outcome by yourself, with limited data.
3. You wait, rethink, and delay, because no choice feels safe.

Days go by. Then weeks. You are “working” all the time, yet big decisions stall.

Things like pricing, your first hire, or which feature to build next can drag on much longer than they should. The work feels heavy, not because the choice is impossible, but because you are the only one holding it.

When you have a few trusted founders to talk to, the same decisions can take minutes:

• “Here is what we charge and why.”
• “We tried that feature, nobody used it.”
• “At your size, do not worry about that metric yet.”

You do not need someone to tell you what to do. You just need fresh eyes and a bit of context from people walking a similar path.

The Emotional Toll: Riding the Roller Coaster Solo

Startup life is often called a roller coaster. The phrase is cliché, but it is accurate.

There are big wins, scary drops, and long slow climbs where nothing seems to move. When you ride that alone, it can be brutal.

Compare these two paths:

• Solo:
  • Lows feel deeper and last longer
  • You question yourself in silence
  • Wins feel smaller because no one really “gets” why they matter
• With peers:
  • You have support when a launch flops
  • People who understand your world remind you you are not crazy
  • You get to celebrate the small wins with people who know how hard they were

Friends and family care, but most of them will not understand churn, MRR, or why a 10 percent sign-up lift is exciting. A partner or spouse cannot always carry that weight with you.

Founders who last tend to have other founders in their corner. That emotional safety net is not nice-to-have. Over years, it keeps you in the game.

You Do Not Need a Co‑Founder, But Isolation Is Not the Answer

At this point, it might sound like the answer is simple: “Everyone needs a co-founder.”

That is not the message.

You do not have to split your company just to feel less alone. What you do need is a group of founders who know your story and care about your progress.

Rob Walling sees this up close with TinySeed, the B2B SaaS accelerator he co-founded. He and his team could have just written checks and dropped people into a Slack group. That would be easier for them.

Instead, they run one-year batches. Every six months, they accept a new cohort, start them on the same day, and move them through the program together. It feels a bit like a grad school class or a high school graduating year.

Why? Because being in a shared “class” gives you:

• Built-in peers who understand your context
• People hitting similar milestones at a similar time
• A natural sense of “we are in this together”

Inside TinySeed, founders get:

• Structured mastermind groups
• An active online community in Slack
• In-person meetups and events
• A growing alumni network they can lean on for years

Many of those founders are solo. In fact, most TinySeed founders are solo founders. They do not have co-founders, but they are far from alone.

This is the key point: not a one-size-fits-all rule about co-founders, but a strong push against isolation.

Co‑Founders vs. Solo: Weighing the Trade‑Offs

Some investors still prefer to back teams with co-founders. All else equal, sharing the load with a true partner can help.

But co-founders come with trade-offs that many first-time founders ignore.

Here is a simple way to look at it:

Path	Pros	Cons
Solo founder	Full control, full equity, faster decisions	Can feel lonely, higher emotional load, more blind spots
With co-founder	Share work and stress, more skills at the table	Relationship can implode, 50/50 split is very expensive

When you split 50/50, you give more equity to one person than you ever will in any other deal. If the relationship goes bad, the cost is high.

This does not mean co-founders are bad. Many great companies are built by pairs or small teams. It just means you should not see “find a co-founder” as the only cure for isolation.

Whether you are solo or not, you still need a group of people who act like a personal advisory board. That is where mastermind groups shine.

Unlocking the Power of Mastermind Groups for Startup Success

A mastermind group is a small, steady group of founders who meet on a regular basis. The goal is simple: help each other win.

Rob has been in three mastermind groups over his career. One of them has been running for 15 years, and they still meet once a month. He credits that group with a huge share of his progress and his sanity.

If you talk to other founders in mastermind groups, you will hear the same thing. Articles like this breakdown of mastermind benefits for small business owners and this piece on mastermind advantages for founders repeat the same core idea. You get knowledge, accountability, and real connection in one place.

What Is a Mastermind Group?

At its core, a mastermind is:

• A small group of 4 to 6 founders
• Meeting every other week or once a month
• To talk through goals, problems, and wins

Fewer than 4 people, and you do not get enough viewpoints. More than 6, and it starts to feel like a crowded meeting where some people tune out.

These are not random founders you meet once at a conference. Over time, they learn your history, your product, and your goals. You learn theirs. You are “caught up” when you join the call, which means you can skip the long backstory and get right to the heart of the problem.

Two or three minds are better than one. Four to six is even better, as long as everyone stays engaged.

Four Key Benefits of Joining a Mastermind

Here are the four big things you can expect to gain from a good mastermind group.

1. Accountability

When you tell other founders what you plan to ship by the next meeting, it is harder to slip.

You feel a healthy push to follow through. You do not want to be the person who shows up every time with a fresh excuse.

This kind of peer pressure is very different from a boss. Nobody is “above” you. You are all in the same game, so the pressure feels fair. 2. Advice and Networks

Your group becomes a pool of shared experience. Someone has:

• Tried that sales channel
• Fired a bad contractor
• Tested that email tool

You also get access to each other’s networks. Maybe someone in your group knows a founder who already solved the exact problem you face. Or they can introduce you to a partner, a contractor, or an early hire.

Many founders in curated groups report the same thing, as you can see in this Forbes piece on curated mastermind groups. You tap into hard-won knowledge that you would never find in a blog post. 3. Gut Checks on Big Decisions

Before you make an expensive mistake, you can run it past the group.

Thinking about:

• Rewriting your app from scratch
• Tripling prices overnight
• Signing a long, complex contract

A few trusted founders can point out blind spots. You can reach out between meetings on Slack, by text, or with a quick voice note.

Over time, it feels good just knowing there are people out there who are rooting for you and willing to give an honest, fast take. 4. Encouragement and Celebration

A mastermind gives you a place where people understand what your wins and losses mean.

They can:

• Encourage you when you want to quit
• Tell you it is okay to shut a product down
• Cheer when you hit revenue you once thought was impossible

You do not get this from most non-founder friends. You may not even get it from your partner. But you can get it from a small group that lives in the same world you do.

How to Structure Your Mastermind Meetings for Maximum Impact

There is no “perfect” format for a mastermind. The best groups all share two traits:

• They meet on a regular schedule
• Members commit to show up and be honest

Beyond that, structure is flexible. Two formats work well for most startup founders.

Hot Seat Format: Deep Dives into Hard Problems

In a hot seat meeting, one person gets most of the time.

For example, in a 60-minute meeting with 4 founders:

• Three people give quick 5-minute updates
• One person gets the remaining 45 minutes to dig deep on a single issue

The focus is always the “biggest current challenge.” It might be a broken funnel, a team conflict, or a product shift. The group asks questions, pokes holes, and suggests options.

Hot seats are great for complex problems that are hard to untangle on your own.

Round Table Format: Equal Time and Steady Progress

In a round table, everyone gets the same slice of time.

A typical meeting might cover:

• What you did since last time
• What did not get done and why
• Your main goal before the next meeting
• Any big win or struggle you want quick input on

This format shines for accountability. You see your own story unfold month by month. The group helps you spot when you are drifting or avoiding hard work.

Rob has mainly been in round table style masterminds, but both approaches can work. The format matters less than the commitment to keep meeting.

Finding Your Mastermind Tribe: Practical Steps to Get Started

Once founders see the value of a mastermind, the next question is simple: “Where do I find people?”

You do not need a massive network to start. You just need a small group of aligned founders who are willing to show up.

Start Local: Entrepreneurship Meetups in Your Area

One path is to start close to home.

You can look for:

• Local startup or SaaS meetups
• Small business groups
• Coworking spaces that host founder events

Meeting face to face can help build trust faster. The downside is that your city might not have many people working on similar types of products, unless you live in a major tech hub.

Go Online: Reach Founders Anywhere

Most founders today find mastermind partners online.

You can post or reply in:

• Reddit communities for startups or SaaS
• Twitter or LinkedIn threads where founders hang out
• Paid or private groups like MicroConf Connect

Rob’s own mastermind groups have almost all been remote. They meet over Zoom and keep in touch between calls through chat.

The key is calendar overlap. You need time zones and schedules that line up enough to pick a regular slot.

If you want more ideas on the kinds of skills you can grow in a peer group, this guide on skills founders build in mastermind groups is a helpful read.

Choosing the Right People for Your Group

The people matter more than the format.

Good filters when you pick members:

• Stage match: Everyone should be in a similar stage. Idea stage founders in a group with $2M ARR founders will feel lost. At that point, it turns into mentoring, not a peer group.
• Similar problem types: It helps if you are all working on related models, like B2B SaaS, mobile apps, or info products.
• Shared availability: If you cannot find a common time to meet twice a month, the group will fade.

You want people who take their business seriously, keep things private, and are willing to be honest, not just polite.

Also Read: Inside Abbode: The NYC Startup Story That Turned $20K Into Millions

Conclusion

When people ask, What is the biggest killer of startups, they often look for a fancy answer. Lack of funding. Weak product. Tough market.

Those things matter, but for many early founders, the real killer is isolation.

Building alone slows your progress, clouds your judgment, and drains your energy. Building with a small group of peers gives you support, speed, and a better shot at staying in the game long enough to win.

If you take one step after reading this, make it this: do not build in silence. Join a mastermind, start one with a few founders at your stage, or plug into a trusted community. Your future self will thank you for not trying to carry the whole thing alone.