First off, most people in general tend to be optimists or to generally believe that things will work out fine. So the idea of catastrophe is not something they spend much time thinking about.

Because of this and other factors I'm about to explore, for most investors the notion of systemic failure is virtually impossible to grasp. Most professional traders are usually under the age of 40 (in fact they're typically in their mid to late 20s). As a result of this, they:

1) Didn't experience the 1987 Crash

2) Have never seen a Crisis that the Fed/ IMF/ etc. couldn't handle

Read the rest at the original source.