When I visited SF for the first time in 2019, it felt really weird that such a rich place would have so many people living in tents in public spaces. Being naive, I saw dozens of tents in Sue Bierman Park and thought they were having an event or something. Then it dawned on me what I was seeing and it never made sense because certainly it doesn't take a lot of money to give these people something so they don't have to live in tents.
Where I live (South America), the city had this situation about 20 years ago and what they did was buy a bunch of cheap land in the outskirts, build small houses and relocate these people. To avoid it being called charity, they "lent" the money that these people could pay in >50 years without interest. And this is a place with no tradition of philantrophy or billionaries. So I'd imagine a single billionarie could fix SF's situation in a blink of an eye, no?