Interesting postscript you have there. If I can predict the irrational actions of other people, can I not be rational?
This certainly appears to happen frequently in the stock market, when only a few people will be rational while the hordes are irrational (e.g. market tops and market bottom being the most visible points of this behavior).
Turtles all the way down.
P.S. If you believe you are the rational one and that other people are irrational, you are acting irrationally.