Came across this interesting article in the Wall Street Journal on why the country built so many condos during the boom a few years ago.  E.g., one stunning stat was that Las Vegas may have a 20+ year supply of unsold units. 

Ultimately, my takeaway is that like any product, there isn't limitless demand for condos and it's easy for investors and developers (not to mention realtors and bloggers like me back in the heyday) to get ahead of themselves — especially if supporting trends seem to corroborate the enthusiasm.  The key here is that legitimate demand drivers like empty nesters, density, pent up demand, millennials, immigration, etc. are all valid but the supply can't dwarf the demand.

Urban centers will continue to represent an important, if comparatively small, part of the rapidly evolving American landscape. With as many as 100 million more Americans by 2050, they could enjoy a growth of somewhere between 10 million and 20 million more people. And in the short run, the collapse of the high-end condo market could provide opportunity for young and unmarried people to move into luxurious urban housing at bargain rates.

But lower prices, or a shift to rentals, could prove financially devastating for urban developers and their investors, who now may be slow to re-enter the market. And for many cities, the bust could represent a punishing fiscal blow, given the subsidies lavished on many projects during the era of urbanist frenzy.

Full article here.