Overconfidence is the bias that follows success. After a string of wins, you attribute the results to your skill (rather than a favorable market or luck), conclude the game is easy, and start taking bigger, looser risks — right before the streak ends.

Why winning is dangerous

A winning streak feels like proof of skill, but markets move through regimes — a strategy that prints in one environment can stall in the next (volatility regimes). Overconfidence blinds you to that shift: you size up and loosen your rules exactly as conditions turn, so the drawdown hits at your largest size (conviction-based sizing done right).

Luck wears a skill costume

Over small samples, luck dominates skill, but our minds credit good outcomes to talent and bad ones to bad luck (process over outcome). A few lucky wins can feel identical to genuine edge, which is why judging yourself by recent P&L is treacherous (recency bias).

The market humbles the confident on their own schedule. The bigger the streak, the bigger the size, the bigger the lesson — usually arriving right when you've stopped expecting it.

The guard

Keep risk-per-trade fixed regardless of your streak, so confidence can't inflate your size (position sizing). Judge yourself by process over a large sample, not the last five trades (consistency over being right). A mechanical system is naturally immune — it doesn't get cocky after wins; it sizes by rule whether the last trade won or lost (mechanical vs discretionary).