Fiat currency is the only thing that makes real estate speculation sustainable for now. Boom and bust cycles use to create bank runs and ghost towns. Automation and outsourcing did the same thing in the midwest, but fiat money can be endlessly conjured into existence without regard to the fiscal constraint of having to payback debtors in a real resource such as specie, which makes speculative losses much easier to recover from and real estate speculation less risky. If I can just print up more bank notes without regard for whether their face value exceeds the value of gold or silver I have, I'm much more inclined to lend it to people who want to turn a profit by making desirable land scarcer. Of course, 19th century Uncle Sam accomplished the same end of making land speculation less risky through land grants and the 7th Calvary.