Risk of ruin is the probability that your trading losses will accumulate to a point where your account fails. Even profitable strategies can have high risk of ruin if position sizing is wrong. For example, a trader with 55% win rate and 1:1.5 risk-reward ratio has positive expectancy — but at 3% risk per trade on a 10% max drawdown account, the ruin probability is 42%. The same strategy at 1% risk drops ruin to just 3%. This is why position sizing matters more than strategy. Calculate yours at propwise.site/risk-of-ruin-calculator.