Loss Aversion
If you present people with an even chance of winning $150 or losing a $100, most refuse the gamble, even though it is to their advantage to accept it. If you multiply the odds of winning — 50% — times $150, minus the odds of losing — also 50% — times $100, you end up with a gain of $25. If you accepted this bet ten times in a row, you could expect to gain $250. But, when people are presented with it once, a prospective return of $150 isn’t enough to compensate them for a possible loss of $100. In fact, most people won’t accept the gamble unless the winning stake is raised to $200.
“Mind Games” by John Cassidy