Greatly increase property taxes on second and subsequent homes. Make the tax not apply to dense multi-unit housing, only sparse single-family homes and condos.

Greatly increase property taxes on second and subsequent homes. Make the tax not apply to dense multi-unit housing, only sparse single-family homes and condos. Make housing covenants illegal. Both of these ideas are super unpopular to the landlord/speculator class, but they'd certainly open up the housing market.