Before anyone jumps on me, billionaires suck, without exception, for reasons I don't really need to go into here, you've all heard them a million times over, and whatever good they do does not offset that in the slightest. None of them probably have been or will be a net positive influence in the world.

That said, you can probably pick out a few good things that any individual billionaire has done (and you can absolutely feel free to debate their motivations for doing those things, many of them I'm sure we're done for tax reasons, vanity, etc.)

Some of the old robber barons like Rockefeller and Carnegie (Carnegie was not technically a billionaire, but if you adjusted his wealth for inflation he would be the richest person today by a pretty comfortable margin) funded a lot of universities, libraries, etc.

Bill Gates has done some good work with vaccines despite his shitty business practices with Microsoft.

Musk is overall a shithead, I don't like him, I don't like his companies, I don't even like his vehicles. That said, I think it's pretty fair to say that Tesla has helped (though he is not solely responsible) to kick open the door for EVs to start gaining wider acceptance and adoption. And SpaceX is doing some exciting stuff, though again I dislike a lot of their methods, disagree with a few of their goals, don't like how they're run as a company, etc. But long-term I think we need to have our eyes to the stars, whether it's for settling on other worlds, mining asteroids, asteroid defense, or if I dare dream it, building a Dyson sphere, or just for scientific advancement for it's own sake, and unfortunately SpaceX is one of the major players in that field now.

Bezos hasn't done anything too flashy that comes to my mind, and like musk he is also a shithead that I dislike for pretty much the exact same reasons, excuse me for not repeating them, but he does have and donate to quite a few charities.

Again, none of that is enough to offset the shitty things they do, but I'd be surprised if you could find any very rich people who haven't at least donated to a handful of charities.