The reason I could be a Mac Developer was the small pond; There wasn't a LOT of work, but there was enough for good people, and it paid well. On balance I /never/ developed anything for windows, because of the 'tree vs forest' problem : Even if you are REALLY fantastically good, there are so many people on the market that you can't possibly stand out.
And that's why I never even wrote a single iOS app, even tho i was a wiz at ObjC and OSX (Imagine a Classic MacOS dev thrown together with a UNIX wiz, and that's me); it was guaranteed to bring in the 'forest' to OSX as well, and make any 'edge' more or less pointless.
Also, from what I've seen, if anyone comes out with a nice app/game, there's a dozen or more group of people who will throw their dev team at copying it immediately, diluting any hope of revenue. It's these guys business model after all, you just can't win, and it's not like you can defend your IP anyway.
So, 2016, I wonder what took people so long to realize it was all doomed but for a tiny fraction of apps.