The reason they work at an investment bank is the same as punters who visit a casino: They aim to make money yet know it is very easy to lose.
This creates a cocktail of fear and greed. Everyone in financial markets knows it. Banks have risk control, but there are traders who evade it.
Jerome Kerviel of the French bank Societe Generale is the biggest loser (€4.9bn). Nick Leeson single-handedly bust Barings, a banking legend, while Irish and Japanese banks have confessed to losses.
As the profits build, rogue traders start to think they are invincible.
But fear comes from the knowledge that as time goes by the odds move against them.
They deal with the fear by trying to mask it.
Leeson drank heavily; Kerviel persuaded himself that his managers approved of what he was doing.