I'll be an armchair economist and throw out my ideas for <i>why</i> this is happening:<p>* Dramatic increase of inequality in the last 40 years means that wealthiest buyers are determining the price of the entire housing inventory. I know too many people with multiple houses. Related to this, the global slosh of foreign capital looking to launder their money, or park their money in tangible assets.<p>* Perverse incentives in the US tax code. Stepped-up Cost Basis means that aging Baby Boomers are highly incentivized to never sell their homes. After their death, their beneficiaries receive a huge tax benefit.<p>* Many of the economically productive areas of the country have zoning laws which restrict new housing development, which cause scarcity, which drive up the value of existing houses for the benefit of existing homeowners.<p>* There has been almost no productivity increase in the construction industry in the last several decades. Due to their inefficiency, the industry is incentivized towards expensive, higher-profit houses, instead of producing higher volume, lower-cost houses.