Story of a Venture-backed startup that failed
medium.com
medium.com
In contrast to this, you never read about the 99 percent of apps that flop. And, in most of these, the creator has probably put in a lot of effort (sometimes even more effort than the winners). Out of 1.3 million apps in the App Store, I'm guessing well over 70 percent are just dead in the water. Effort expended that failed.
After reading the story, I can't really figure out what they did wrong.