Which is a very good reason not to believe in market forces.
In fact, a fairly good definition of "civilization" would be "a bloc of people who have organized themselves so as to overpower natural forces and configure their lives in accordance with their own preferences/values/criteria".
TL;DR: I don't go around claiming hurricanes are "optimal", so neither are market crashes.
http://www.theatlantic.com/magazine/archive/1999/03/the-mark...