> Anyway, are people making lucrative careers out of bug bounties?
Not really, no.
Sure, the top 20 hackers on H1 do make a very decent living (you can listen to the story of Dawgy-G on Darknet Diaries ep60 about that). But realistically, if you are that good at it you can get paid much more doing a 'real' infosec job.
Bug bounty hunting platforms like H1 do give you the freedom to work whenever you want, wherever you want on your own terms. Basically gig economy.
Personally I do bounty hunting every now and then because I enjoy the learning experience from it. But looking at the time it takes me to discover a bug and writing a detailed report only to receive a couple hundred USD for it, it really isn't worth my time in a professional sense.
I'd say I make about 25USD/hour from it. Of course this is highly dependent on your skills. And it is also highly dependent on where you live whether 25 USD/hour is actually enough to make a living.
Sometimes you can get lucky and stumble upon a valuable bug and make a couple of grand for only an hour worth of work, but most of research you'll do will yield you knowledge, not money.