This is advice from an investor who has backed 220+ startup companies and seen 20+ positive exits, written for other investors, so they would not make the same costly mistakes I have made.
Each of the four mistakes below has made me turn a founder down. Some of those founders went away, studied, came back, and we invested later. I have made some of these mistakes myself, and I still make one of them. They are the same whether the founder aims for a unicorn or a trade sale, and angel investors fall into every one of them.
1. The product has no buying customer behind it
The founder has already built something. The product exists. But the understanding of the industry stays on the surface, or the whole plan rests on a dream nobody has tested.
Too often, angel investors get excited about the product. Nobody has verified it with a buying customer. What is missing is Buyer Proof: an economic buyer with a costly problem, where solving it creates measurable value. Weak proof is interest, compliments and no budget movement.
In my experience, the materials show whether the founder has it. The same thing can be written as activity or as commitment. "We have interviewed 40 potential customers." "A pilot is running with two companies." "Three LOIs signed." Each reads like progress, and each cost the customer almost nothing to give.
Commitment looks different. A budget moved: somebody paid, and the founder knows from which line. A customer changed its process or its contract. Two customers bought the same way, for the same reason. A costless yes and a costly yes are different facts. Nice meetings do not pay invoices.
This is the mistake I still make. When I entered the Swedish market, most of my assumptions were incorrect. Much more capital was tied down than I had planned for. The market was harder and more competitive than it looked from the surface. And many of the customer comments I had collected beforehand were more compliments than facts.
Many times the investor also thinks he is investing in a huge market that actually does not exist. One of my early angel investments, where I was among the first to commit, started from a dream of roughly 14 million potential customers globally. Out of seventeen companies that fit the narrow profile the founders first went after, thirteen had bought. Thirteen out of seventeen was a repeating buyer. Against fourteen million it looked like a rounding error, so the founders kept chasing the dream. It took a long time and a great deal of unnecessary spend before anyone asked who else looked like those thirteen. The answer was a real segment, large enough to build on, and cheaper to serve than the market they had imagined.
The popular story says a young outsider sees what the industry cannot. The data does not support it. A study of US Census Bureau data on startups found that the mean founding age for the one-in-a-thousand fastest-growing new ventures was 45, and that prior experience in the specific industry predicted much higher rates of success (Azoulay, Jones, Kim and Miranda, American Economic Review: Insights, 2020).
2. Nothing gets a no
The founder sees a larger customer segment, another country, an adjacent use case, a competitor raising money, a new technology trend, and concludes: we should go there too. The team stops trying to win one thing and starts trying not to miss everything.
Investors have their own version, and I know it from the inside. My FOMO was an inability to say no to money or business that looked attractive, not the excitement people assume.
As a young angel investor, my gut said no, clearly, every time, and I overruled it anyway. I cannot honestly reconstruct a justification for it now. What overruled it was the pull to dream big and believe the story before the evidence existed. I lost substantial amounts of money behaving this way. The bad checks were the visible cost. Focus was the real one.
In 2010, at a strategy session at Harvard Business School, a professor said something I have carried since: a clear strategy emerges after enough no-decisions. It took me years to realise it described my own biggest weakness.
A no holds for the present, not forever. It can change when the evidence changes.
3. A high valuation is read as proof
For founders, a high valuation typically means validation of a great idea. They typically do not understand how much it impacts the future. The investor's side of this mistake comes from small or non-existent knowledge of the actual exit market.
What is missing on both sides is Exit Proof: a rational buyer would pay to own something they cannot easily build. Each round raises the valuation, and each valuation raises the minimum exit the cap table can accept. Fewer acquirers can justify the price. An angel who accepts the price without knowing who actually buys companies like this, and at what price, makes the same mistake as the founder.
The arithmetic is simple. A €20M exit with 70 to 80% ownership is life-changing. A €200M exit with 5% ownership is clearly less so. At 75%, the first founder takes home €15M. At 5%, the second takes home €10M, after building a company ten times the size.
The extreme version is ambition used as a valuation mask. The story is inflated so that no proof has to carry the price. Investors fund the narrative, the founder inherits the expectations, and the gap is discovered later, expensively.
4. The dream world of the Silicon Valley winner
Really often, a founder refers to a book by a Silicon Valley winner and tells me he thinks the same way as the writer. Investors fall into the same dream world just as easily.
Not every Silicon Valley book is a success story. The ones read in the Nordics are. They are written about the end result, the unicorn, and how to get everything right on the first try. The writer has forgotten, or left out, the situations where he made mistakes.
I fell into it as an investor. When I started angel investing in 2008, I believed a successful entrepreneur could recognise winning opportunities on sight. Twenty-seven years in gaming, so surely the pattern library was paid for. In December 2011, three partners and I launched an accelerator on that belief. We failed miserably. The thesis we ran was imported from the US, and it does not survive in small markets: the buyer density, the capital maths and the exit paths are different.
We went into study mode. It took years of learning what actually happens in this market. The thesis that came out of that failure has carried my investing and our funds since.
Where this stops working
To be successful, an investor needs a clear strategy. Either you follow it, or you develop a new one.
I also know the cost of my own filter. I have passed on companies that later became extremely successful. Discipline means missing some good opportunities on purpose.
What to do in the next meeting
Spend more time with the founder before committing, to learn the depth of their understanding.
Here are four of the questions we ask. We use them to separate capability from wishes.
- What did the customer do that they did not do before? This is the Buyer Proof question.
- Has anyone other than the founder ever closed the same deal the same way? This is the Scaling Proof question: does the same system repeat without the founder present to carry it?
- What missing proof does this funding buy, and what does it not buy?
- What will you do when the forecast does not come true?
Some founders I turn down go back and study. Sometimes we invest after that. The ones we backed came back with lessons they had learned from customers.
More scars than trophies.