Overconfidence is trusting your own judgement more than the evidence supports, especially about things that are genuinely hard to predict, like where a price goes next.
Feeling certain leads to bigger bets, less checking, and ignoring the chance of being wrong. The feeling of certainty and the actual odds of being right are not the same thing.
Ask a room of drivers if they're above average, and about nine in ten say yes, which is mathematically impossible for "most" of any group. Investing decisions show the same pattern.
The more confident you feel about a single bet, the less likely you are to write down why, or to set a point where you'd admit you were wrong.
Writing a decision and the reason down before acting, every time, slows down the overconfident jump straight to action.
Feeling certain is not the same as being right. Write the decision and the reason down before acting.
Write your next decision and your reason.