Me.

Well, to be more specific, my thought patterns. There are a variety of destructive psychological mistakes that continuously cause entrepreneurs to make poor decisions. These patterns are very well documented and talked about, but they continue to haunt entrepreneurs on a daily basis.

Sow a thought, reap an action; sow an action, reap a habit; sow a habit, reap a character; sow a character, reap a destiny. – Ancient Maxim

It’s actually quite impressive how good human beings are at convincing ourselves of things that aren’t true. The primary one that killed my first startup is confirmation bias.

The first principle is that you must not fool yourself — and you are the easiest person to fool. – Richard Feynman

Simply put, confirmation bias is your brain tricking you into somehow thinking that you’re special and that reality doesn’t apply to you. For example, some studies have shown that 21% of young people, when asked if they’d be rich when they were older responded with,”Yes, I’m going to win the lottery.”

If there’s a minuscule chance of winning the lottery, how can 21% of the people feel like it’s going to be them? It’s unrealistic.

Confirmation bias manifests itself commonly in entrepreneurship when founders are determining the viability of a new idea. The startup world has changed significantly with the advent of the lean startup movement where entrepreneurs are now developing hypotheses and testing them, but the experiments are often flawed.

Everyone wants to feel like their different – that they’re special. Entrepreneurs want to think that their idea is revolutionary and guarantees success because it was their idea.

This is precisely what happened with my first startup. I had won two business plan competitions in my MBA program for, what I thought to be, an absolutely ingenious startup idea.

I was convinced the idea was good because I had it.

I spent the next six months engineering a prototype and then launched it to the world with the expectation of being overblown with market demand.

The actual result: crickets.

It solved a problem that nobody had. Paul Graham, founder of YCombinator, says that the number one killer of startups is “making dog food that dogs don’t want to eat.” If I would have spent one day going around and talking to my hypothesised target customer without letting myself be tricked by my own confirmation bias, I would have known that the business wasn’t going to work.

Live and learn.

I’ve invalidated a handful of ideas since then. And validated one. You remove confirmation bias by trying to be as ultra-realistic and objective as possible. Pretend a stranger was telling you this idea. Tell some people you know your idea, but don’t tell them that it’s yours. Say that you heard about it and weren’t sure what to think.

Really pay attention to negative feedback and solicit it, particularly from friends. …Hardly anyone does that, and it’s incredibly helpful. – Elon Musk

Spend some time learning about customer development and how to accurately formulate experiments.

I can confidently say, the faster you start exercising the muscle of rigorously removing confirmation bias, the quicker you’ll find yourself with a successful business.

Sign up for my email newsletter for tips on how to conduct customer development and talk to your customers to validate or invalidate your ideas.