Loss aversion
Loss aversion makes a loss feel stronger than a gain of the same size. It pushes you to hold losers and cut winners.
Described by Daniel Kahneman and Amos Tversky in prospect theory, it explains a very common behaviour: refusing to take a loss in the hope that price comes back, while banking a small gain quickly for fear of seeing it vanish.
The result is an inverted trading profile: small wins, big losses. Even with a high win rate, expectancy turns negative.
The cure is mechanical: a stop placed at entry and never widened, a target set in advance, and thinking in R rather than in money. Thinking “−1R” makes a loss easier to accept than “−€250”.