This would be ideal, but as so many people own their own homes, this would be politically unfeasible. I would increase property tax exponentially after the 5th

This would be ideal, but as so many people own their own homes, this would be politically unfeasible. I would increase property tax exponentially after the 5th property or so, to hit the big landlords and investment funds, while keeping the homeowners and small landlords appeased. Then take that money and build or buy public housing to rent for cheap prices, to bring the prices down for everyone.