You're omitting a major component of the demand side: investors and speculators. If the market was just made up of the people who are looking to live in those homes, the market would be reasonable for those people. But we have a massive amount of investment funds looking for returns in an uncertain market, plus near zero interest rates for the near future. The number of investors who are buying houses they have no intention to live in is skyrocketing, either to rent out, to flip, or just to hold vacant in the hope values keep rising.