I believe our supposed inability to predict economic bubbles (and other financial crises) is mostly just tautological: those crises we can predict never happen because they are "self-falsifying prophesies": If enough people believe the stock or housing market is overheating, they will stop buying or might even speculate against further rising prices.

Thus, any bubble that does manage to grow to significant size before bursting is necessarily "unforeseen". (of course because of that thing with the monkeys, the keyboards, and online message boards, the will always be plenty of people that did see it coming, but I would wait to buy their book until they do it a second time).

I know it's always trendy to hate on economists (some people have taken that idea all the way to creating cryptocurrencies and reinventing economics along the way). But comparing, say, the 2008 crisis with the 1920 or even the 1970s, I can't shake the feeling that maybe economists have become slightly better over time. The gold standard fandom that was all the rage for a while essentially rests on the idea that interventions by central banks are worse than doing nothing, and the evidence now seems overwhelming that we can do better than this (admittedly low) benchmark.