Where the author made a mistake was in trying to make "what the market wants" rather than just making stuff he/she actually wanted to make and trying to see if it was possible to make money from it. If you try to make "what the market wants" rather than what you want, you're going to make garbage and further saturate a market that is already filled with garbage that was designed to cash in on "what the market wants".…
Eh, at the same time, I think the problem a lot of entrepreneurs have is that they overfocus on "what you are interested in" instead of "what the market wants", and therefore build something that nobody wants. If you can find a perfect intersection, that's beautiful, but probably uncommon. Some of the most lucrative businesses are stuff like (anti)fraud/security/payments that is pretty darn drab.
Do what the Market wants means making a tradeoff in favor of earning more (and becoming rich(er)).
Doing what you want to do means making a tradeoff in favor of your happiness. You will perhaps earn less, but what you do is more in tune with your values.
A tradeoff is not always required and both of these motivations may become synergies, but in the authors case, I think this is what happened.