There are tons of indie game success stories. Even more so if you count modest success from niche games. Jeff Vogel has been doing it since 1994, when finding an audience and taking payments on the internet was much, much harder.
Making niche games actually strongly resembles more "serious" software products, because you have a group of potential customers who have a decent idea of what they want and a market that isn't providing it. If you're lucky, you'll find pages and pages of forum posts describing the sort of things they like.
Expecting to make the next Angry Birds is stupid. But making games with the expectation of a decent income is entirely realistic, and just requires the same marketing skills as anything else.