For the sake of argument, let's assume that an indie game takes around a year to develop. (Most take more time)
This is what you can achieve
Level 0 [Hobby]: You make 0-100 $$$ on your game because you are not really trying to make money. You're just about learning and having fun. You do not make a quality game, and you lack the skills to market your game. ( Most people on this site )
Level 1 [Amateur] : Most "sell-able" indie games will earn less than a 1000$ dollars (not justifying their development time). If you're serious, but this is you're first attempy, this is what you will probably create
Level 2 [Professional] : A few successful indie games earn 10s of thousands of $$$. ( the same you would make in a salary position ). If you're a successful professional indie gamedev, this is probably where you'll end up. ( If you have to ask the above question, I doubt you will make it this far on your first (or second) try )
Level 3 [ Indie Rockstar ] : A handful of indie games per year make a few millions of $$$. If you're successful, and extremely lucky. ( Braid & Flappy bird are an example of this ). This is extremely rare. I'd be very surprised if there is a single person on this site who has made this kind of money from working alone on a small game.
Level 4 [Unicorn] : Some unicorns earn 100s of millions of $$$: Maybe one game per year or less. Mine-craft, Angry Birds etc... But they are not small projects by the time they become unicorns. If you're extremely lucky, and know how to grow your business (you basically need to ride the wave into becoming a AAA company ). Besides being lucky, you need to be extremely talented on the business side of things.
There are two ways to break in:
1. Alot of game studio founders worked for other studios first. So start by working on another professional game. It can be an indie game, or a studio game, or an "evil" F2P game made by a company with lousy ethics. Your goal is not to live your dream, your goal here is to learn while possibly getting paid.
2. Keep creating small games with the goal of making more and more money each time. If you're a noob, make sure you have a mentor/colleauges to learn from. Don't know anyone? See option 1 above.
3. Keep making games just for fun. If you end up liking it, see option 2 above.
