Which can be easily resolved by taking building regulations from NIMBYs and giving them to YIMBYs and letting people build build more or less anything anywhere. 1000 billionaires having 5000 houses have no effect in comparison with hundreds of thousands of houses not built because of regulations.

Real estate is not the medium of exchange. And the answer there is to build more real estate and have high taxes on any property that isn't a primary residence.

There's "rich people" buying houses, which are investment funds that buy property to rent - that is still availalbe on the market and isn't decreasing the supply of housing.

Rich people buying homes for personal use can't have an appreciable effect on pricing. You couldn't afford a billionaire's eighth home in whatever city even if it were available for sale anyway.

i dont think the cause of housing shortage is billionaires with their 3 vacation homes. there's just not enough of them to make a difference.