The wealthy aren't waiting around to buy/sell houses per se, they're trying to get a maximum return on investment. Adding enough supply so that housing isn't an investment vehicle removes those incentives.
Who will add luxury apartments or affordable apartments except for the already wealthy? Who has the incentive to build enough luxury apartments, to stop housing behaving as an investment vehicle?
There are many many factors that are contributing to high costs like euclidean zoning that took off when the US had less than half of its current population. It's literally illegal to build multifamily housing in vast swaths of the US.
It's very clear that some sort of housing reform is going to be needed, as overly restrictive zoning, suburban sprawl, and it's associated housing costs have become unsustainable.
This isn't some fantasy either, Japan has very reasonable zoning and housing is generally not an investment vehicle there. Sure there's other contributing factors like a declining population, but it all leads back to supply and demand!
how sure are you about the validity of the claim you just made? Note the link below does not include cash buyers.
https://old.reddit.com/r/toronto/comments/14zdsia/housing_pr...
The point I've made, is that demand is not just people wanting houses, it's also their ability to pay. There's some magical thinking out there that if investors build 'enough' luxury homes the poor will be able to afford homes. This is a falsehood.
I can't speak to Japan, however I don't think it ever accepted the level of homelessness that the west takes for granted. I would wager that the Japanese government builds more housing projects for the poor than the west.