usually one man band game is
taking long time to make
mediocre quality
is it possible to make a living by making game full time???
I don’t know, but I think you should ask Dong Nguyen, or Andreas Illiger, or to a lesser degree… Notch
Possible? Yes. Easy? No. Likely? No.
As a one-man band, you have to split your time between development and marketing. Without both, you’ll never make a cent. As you said, this usually both increases the time to create a game and lowers the quality of the result.
However, most one-man game success stories seem to focus entirely on development. What gives? Well… they basically got lucky. Their game struck a niche chord, got noticed by some influential people, and it went viral. Do not expect this. These developers are the extreme minority. Look up the “availability heuristic” and “survivorship bias” if you’re still finding yourself looking to them as an example.
Not so far no. Think of it as an expensive hobby. Or look to set yourself up as a freelancer early on and do the networking and marketing accordingly.
Also think of the app stores not as a potential revenue stream but more like the lottery, due to the limited to almost none existent window of opportunity your game will have when dropped into the river of new apps and games appearing daily.
Which brings you back to marketing and networking.
Is it possible to make a living making as a one man band??
Well I’m doing it. So yes.
I wouldn’t ever want to make games for a living. There’s just far easier things to do that pay much better.
If you ever did make a living off making games being a one man band I’d say you’d have to work so hard churning out constantly would probably lose its appeal pretty quickly.
The answer you’ll get for that is never going to be “yes, go for it!” Because it depends on what you can do, and also what you’re willing to do.
Ask yourself this… if you can manage to make games worth playing, without paying anyone a salary, or sharing profits… then why wouldn’t it be even more likely that you make a living on your own, than in a team?
There’s always some inefficiency involved in a teams, that’s beyond each individual capabilities… lack of: team work, team compatibility, team synchronization, team reliability, etc. And on top of it, they have to share profit in the end.
Working alone your work doesn’t depend on someone else’s completion of their part, or vice versa, so you don’t waste any time waiting, but no one’s hurrying you either. And you can go back and fix, change stuff at any time, without causing conflicts with other people’s work. Your efforts are placed exactly as you expect.
Having said that, it’s still a whole lot of work to make a game on your own. And you have to be efficient enough on your own… to release games that give enough revenue to work on the next game.
Releasing games faster, knowing what works and what doesn’t sooner, could very well mark the difference between success and failure. That’s where a bigger teams can really benefit from their brute force.
You’re asking the wrong question. However, the answer is that it’s possible, and it’s also VERY UNLIKELY. And, you may find value in these answers to similar questions.
Gigi.
whether you think you can, or you think you cant, you are right! 
Yes it is, I’m making a very good living as a one man band.