I just read an interview with Michel Houellebecq (The Elementary Particles, in German Elementarteilchen). He said it's always the others who decide if you're a writer or not. And so he's aked if you can't be also a writer without any success on market. He strongly negates and puts it like there has to be people who say "That's good, what you're doing. Keep it up!"
Disregarding the fact that financial success is always a type of more or less indirect endorsement or demand for continuing the work. I think it's pretty the same with independent game developers. Without financial success only the most iron developers would continue making their games, if there's additionally no support from at least a small fan group. Things are getting interesting if on the one side an indie has financial success, but on the other side he's faced with (idealistic?) criticism by some who don't like the games or the way the payment works and try to deprive her or him from being an indie.
So in my opinion Houellebecq's view is more or less also true for indepdent developers. It's always the others who decide if you're an indie game developer or not. So I don't think there are developers who really ONLY make games for themselves, without considering an audience, at least at some points. Well, it's a bit tautological: If these guys really do exist, we wouldn't notice them because they wouldn't release anything on the internet or anyhwere else. That would lead to another idea of when making games only for you, setting rules for yourself, why not just play the game inside your head? But that's another story...
Another memorable thing about Houellebecq, asked about his writing rhythm: He said that he gets up at 3 or 4 o'clock in the morning and then writes for four or five hours. Afterwards he gets drunk.