California has several times as many unoccupied housing units as homeless people. California doesn't have a hard shortage of housing units, certain people that need housing in California have insufficient material means to convince the people that own existing unoccupied housing units to rent or sell to them.
It also fails on the other end because there are many alternatives to local housing other than homelessness, like selecting less local housing with an unreasonably long commute or living in units designed for fewer occupants in violation of the fire code. You essentially have unaccounted for over-occupancy. People having more money doesn't solve any of those problems without more housing for the money to buy, and interferes with solving homelessness as well because higher wages in general could cause people in those situations to move to existing unoccupied units before the existing homeless do.
They're not. If you need housing for two million people and you have housing for one million, and you refuse to build any more housing, you don't have enough housing. It doesn't matter how much money people have because whoever has the most would just bid up housing prices so they can have it and there would be people left at the bottom without it.
Whereas if you had enough housing for twice as many people as actually live there then housing would be very inexpensive and even people not making very much money would be able to afford it, because getting a unit wouldn't require outbidding someone with a lot more money than you.