Irrational exuberance? May be, but...

Irrational exuberance? May be, but it'd be unwise not to ride the wave while it lasts.  Investors can make unthinkable profit during a time of "irrational exuberance" such as in the 1990s before the burst of the dot com bubble.  Too risky to ride on a bubble? May be, but a simple trailing stop-loss should easily void that risk.  I believe the key is not to recognize that we are in a bubble (and get scared off the market too early), but rather to recognize it when the bubble bursts (i.e., being stopped out at the early stage of a bubble burst) so that we do not reenter the market while the burst is still on going.  The biggest risk for investors is never during a bubble, but rather after the burst of a bubble by reentering the market too quickly (高手死於抄底).

My two cents.