The US has been printing money since 1973. Generally speaking, when you debauch the currency you get inflation. For decades we've been pushing that inflation into stuff like real estate and stock market asset bubbles. This will likely continue in first rank cities since the printed money is going to elites and institutions who reside in such cities.

It's pretty interesting that the recent changes in the tax code have had the effect you'd predict: since you can't deduct property taxes and interest off your federal taxes in the same way as before, real estate has defacto become more expensive.

I haven't closely studied Tokyo real estate values, but I remember at one point Tokyo's real estate was worth more than Japan's GDP or something absurd like that. I think that bubble eventually normalized. https://en.wikipedia.org/wiki/Japanese_asset_price_bubble