Quote from sle:
People who have blown up (including quants at LTCM, which is a fashionable topic) have exhibited either some sort of fallacy in their numerical analysis or in their critical thinking. Dumb luck and access notwithstanding (which pretty much excludes all market makers), people who were and are making money posses both critical thinking and the numerical skill set in one or another form.
+1.
The fatal mistakes of hubris tend to show up as logic errors of exposure or neglect that amplify mortality risk. Rocket scientists don't always think things through, especially when possessed by delusions of grandeur. Paul Tudor Jones: "Don't be a hero. Don't have an ego."