Borderline
Markets often exhibit behavior bordering on the delusional – frequently from the wrong side of the border. Investors seem unable to disassociate specific investment opportunities from broader economic realities – how many corporations in the history of the world have ever justified a P/E of over 100? Yet, from time to time, people will fall over each other to invest in these "opportunities", seemingly oblivious to the enduring nature of competition in markets.
Of course, financial markets are just a peculiarly public forum for demonstrating this irrationality, and one in which it's possible to quantify the scale of it, albeit only in hindsight. But human mass delusional behavior isn't confined to markets, it's just other social settings make it more socially acceptable. To be human is to be be mad, but we don't have to be poor as well.
