Very little research currently goes into attacking aging directly - as opposed to handling things that are in no small part downstream from aging, such as heart disease. A big reason for poor "longevity gains" is lack of trying.
You can't rely on billionaires to fix everything for you. The kind of research effort that would be required to make meaningful progress against aging would likely demand hundreds of billions, spent across decades. Few billionaires have the pockets deep enough to bankroll something like this, or the long term vision.
Getting aging recognized as a disease and a therapeutic target, and getting the initial effort on the scale of Human Genome Project would be a good starting point though.
If there was understanding that a drug "against aging" is desirable by the healthcare systems and can get approved, Big Pharma would have a reason to try - as opposed to developing drugs for other things and hopefully stumbling on something that makes progress against aging by an accident.
[1] https://www.thelancet.com/journals/lanonc/article/PIIS1470-2...
Two decades of this kind of research spending add up to $100 billion. And most billionaires are closer to $5 billion rich than to $500 billion rich.
It would sure be nice to have an infinite money glitch billionaire who cares a lot about funding anti-aging research and lobbying for anti-aging efforts, the way Musk cares about space exploration and trolling people online. We're lucky that at least some neglected fields get billionaire attention like this. But we can't rely on that happening.
It's why I stress that aging should be recognized as a disease. If we had the likes of WHO and FDA in agreement that aging is unwanted and treating aging is desirable, even if it can't be done yet, it would shift the perception considerably.
It would make it easier for billionaires to contribute to anti-aging research as a philanthropic effort - but it would also open many doors in terms of research funding and corporate investment.