It's all a policy choice, though. The USA could, for example, increase property taxes on non-primary homes and offset investor losses by adding an incentive to sell non-primary residences for some length of time (say, 2 years). The problem isn't that the solution is a mystery. It's that we barely live in a democracy and the people that own multiple homes have more power than the young-ish (median first time home buyer is up to 40 years old now) population that doesn't vote in large (enough) numbers to offset the power imbalance.