Risk of ruin: why a 60% win rate can still blow up your account

Win rate alone tells you nothing. A strategy with a 60% win rate but losers twice the size of winners has negative expectancy.

Expectancy = (Win% × Avg win) − (Loss% × Avg loss)

And even positive-expectancy systems can hit long losing streaks. At 2% risk per trade, ten losses in a row is about an 18% drawdown. At 10% risk, it's catastrophic.