> If you build a $5 million dollar house, and a multimillionaire buys it as their fourth house, this does not reduce housing costs for anyone. That’s not neces

> If you build a $5 million dollar house, and a multimillionaire buys it as their fourth house, this does not reduce housing costs for anyone. That’s not necessarily true. If you build a $5m house where there was previously no house, and the multimillionaire buys it, then they’re not buying some other $4m house, and someone could buy that instead of something else, etc. For this to work, you need a situation where building n houses does not create demand for approximately n houses.