Nearly 30 years since Greenspan's "Irrational Exuberance" speech in December 1996. Wild to think how that phrase became shorthand for market tops — yet the S&P more than doubled in the following three years before the dot-com crash.

Reminder: calling a bubble early can cost you just as much as riding it too long. Timing is everything, and even the Fed chair got the timing wrong. Markets can stay irrational far longer than your patience (or capital) can last.