It's really very simple supply and demand game. As the population grows, the demand follows. The globalization plays an ironic role as well - the value created in China from producing most of the physical items we consume gets parked in real estate and stocks in the West because the Chinese political system is too risky. Same happens with Saudi/Russian oil/gas money, except the typical millenial westerner is completely cut out of this loop and is wondering why does the pay from their job (that often has a near zero impact on the company's profitability) barely cover the rent.

On the other hand, the supply is physically limited due to the geographic constraints. Sure, we could build more condo towers, but that would just delay the problem for a generation or two, while lowering the life quality compared to detached right now.

I think, a better solution would be a wider acceptance of telecommuting to relax the geographical constraints, and trying to put more people in the loop of the economic value creation to give them more purchasing power.