The asymmetry of losses
A 50% drawdown requires a 100% gain to recover. During the 2008 financial crisis, the S&P 500 lost roughly 57% from peak to trough. An investor who avoided even half of that decline would have been years ahead in terminal wealth. This asymmetry is the central reason risk management deserves at least as much analytical effort as return generation. Systematic approaches remove the timing problem by defining rules in advance, evaluated against historical data, and executed without emotional interference.