Vacancy taxes are good but not enough by themselves. S.F. needs more housing, including middle housing, three or four story buildings with multiple units. The market dynamics that apply to shampoo and fridges apply to housing as well. Prices are elevated because of an imbalance between supply and demand. Supply must rise to match demand. Let investors and speculators snatch up new housing units, at least at first. Investors do not have access to unlimited capital. If $100B worth of new housing hit the market overnight, it would be impossible for investors to buy them all. Keep building housing until investors run out of money and normal people can start buying them.