Not sure this is feasible. A) People can hide how many houses they "own" rather easily. B) People with 10,000 houses have 10,000 times the economic incentive

Not sure this is feasible. A) People can hide how many houses they "own" rather easily. B) People with 10,000 houses have 10,000 times the economic incentive to run for office and/or press elected officials to make things easier on them. The best approach is to press for over-development of housing. It doesn't matter if someone owns 1 house, or 1000 houses, so long as there is more than enough homes for everyone. Idea: have a property tax line item that's based on the ratio of population / housing units. The higher that ratio, the higher the tax. The tax revenue is used to cover the costs of constructing more housing units, which lowers the tax.