Seattle is not alone. Vancouver, Sydney, London and other cities all have experienced the same boom. The global economy is currently booming, wealth is shifting from middle class to upper class. Building homes have become cheaper but since transportation services are still outdated, more and more people want to stay in the same place. The super wealthy are leveraged by the banks and think housing is a great investment so they squat on swaths of buyable property and rent it out.

If a City implements a solid transportation system that gets you in the burbs within an hour, then the prices drop. Prices are simply a matter of demand and supply, and supply is artificially capped.

The truth is, humans are terrible long term decision makers for the good of a large population. Personal agendas always get in the way.

Prop 13 is the coup de grace that exacerbates all the other issues that contribute to demand outstripping supply by removing the tax pressure that should've been incenting more density and liquidity in the housing market.

Seattle's real estate market has some but not all of the same pressures: too prescriptive of zoning that requires single family homes for no good reason and booming economies adding jobs at a faster rate than housing stock. But Seattle builds faster and taller in the median case; though the tall building seems to go through waves of either being all apartments or all condos.

Seattle has built enough housing supply that rents actually dropped earlier this year (https://www.seattletimes.com/business/real-estate/seattle-ar...) and the median clearing price is less than half of the San Francisco rate.