There are 750 billionaires in the US. I get your point about them not having enough real estate to host 1000 persons each, but usually, people considerably underestimate how many billionaires there are and how much they're worth.

They wouldn't have to give up their home to shelter 770k people. They could to it with less than 1% of their combined wealth.

That's where making them give their wealth away comes in. The homeless shelter thing is more of a "fuck you" than a practical solution.