Most indie game devs do not turn a profit on their work. The numbers vary from year to year but on average an indie game that launches on Steam earns in the $1000-5000 ballpark, which limits how much time you can profitably put into it.
Of course, if you can hit it big the numbers can be pretty good. But not many games manage to hit it big. It used to be much easier to get visibility as an indie a long time ago, but that's partly because there weren't very many indie games on storefronts like Steam, Xbox etc at the time so being there got you attention. Now hundreds of games come out every day and are competing with you.
I do know multiple indie devs who do it for a living, but they tend to have to supplement their game revenue with contract work, or they split the burden with a spouse who has a regular job.
Personally I've worked on multiple shipped indie games and have never earned enough off that to pay rent, though it was nice to get a few thousand in post-launch royalties over the span of a few years + the initial amount I earned working on it. I always had to supplement things with traditional freelancing or a day job.