It happens, but at the same time highly successful games, like Summer Time Saga and What a Legend were the most ambitious and also the first games of those devs. This has to do with wasting time "practicing" vs putting all of your life into one fantastic game.
A mistake I personally made, and many devs made is that they believed they needed to practice with many smaller games and projects. Personally I made five games over the last five years, almost all of my free time for two years, and then I left my job and worked for three years full time living on savings making games.
None of those games were very successful because a small game with a small story very rarely will get people's attention.
If I could go back and do things differently, I would have spent those five years working on only one single game. As I got better at writing, I would have went back and rewrote parts of it. As I got better at graphics I would have went back and redone the the art. When I decided that 2D art was something I preferred, I would have gone back and redone the art to be hand drawn, and as I improved in my drawing abilities I would have continued to redraw and improve the art to make it better. As I learned which game engine people preferred, I would have transferred it to a new engine, and continued to improve it in all areas as I learned...
but I would not have spread those five years out over multiple smaller games. This isn't a mistake I will make again in the future, but one that people don't realize how bad of a mistake it is until they've actually gone through it.
Hopefully another up and coming dev reads this and can avoid a good portion of their lives lost on small projects.
Another mistake I see devs make is those who will spend five years without going back and redoing the art and writing, only pushing forward with their story which is just as bad.