>>> Mostly, these developers don't make anything. They spend months and years in almost solitude making something no one will play. Games take a huge time investment to make before anyone is at all interested. It's the starving artist profession of the nerd world.
Yeah, the Indiepocalypse.
The thing is, a lot of indie games... simply are not fun to play. And that's ok, it's hard to make a game which is fun to play. It's fine. [0]
You can treat indie games as a hobby, just have fun, call it 'starving art', whatever, but don't be shocked that people are not paying money.
On other hand, treat it like a business, with a solid product, market research, plenty of feedback from the outside (echo chamber is no good for a product that you are working on for years), marketing plan and some marketing budget. Even then, you have a chance of failure, where failure is that the revenue does not cover the costs. However, the odds are more in your favor.
These two extremely distinct segments (hobby v business) are both under the 'indie' label, however, their chances at succeeding are extremely different.
[0] I won't even talk about the platformers (there are dozens, if not hundreds, of them released every week) and they all are largely the same.