It does seem like making the city undesirable for the wealthy would be only way to get prices to drop (stopped being affordable a while ago)
Who are the wealthy in this case? Because if they are wealthy they probably just Uber from their gated/secure location to wherever they are going and avoid the problem if it gets bad enough walking on the streets.
San Francisco has to build but ultimately there is just too much demand. It’ll never again be “cheap” just like Manhattan will never be cheap.