It's always something. You had a gold and oil bubble in the 1970's, an S&L crisis in the 1980's, a tech market bubble in the 1990's, and now a housing bubble.
The herd stampedes from one fad to another (leaving a few laggards from each generation to pine for an earlier fad). Don't be shocked.
Nor should you be surprised when the next big thing turns to a bubble and then a bust. I'm guessing bonds, but who really knows.
And as always happens, a few guys at the front of the herd make a huge score, add to it by selling their "secrets" to the rest of the herd, increasing its size, and a bunch of people at the back of the herd are left holding an empty bag, wondering what went wrong this time.