That's because most people do startups that are destined to fail. I've done plenty of those myself! The problem is that we think we can get away with building solutions looking for products. While a few of those do well, in general, that is a recipe for failure.

In other words, our success was because we identified a critical missing piece in a profitable industry and built exactly what people were asking for, and more importantly, willing to pay for.

After that success (and a couple more after it), I refuse to ever build something without finding customers first. You have to build products people want, not try to convince people into believing they want your product.