Some time ago, I did something quite typical: whenever the market moved, I got emotional; I wanted to buy when it was rising, but couldn't hold on when it was falling. I kept flipping back and forth several times, and in the end, my account hardly changed.

The most ridiculous part is that a few times I actually saw the right direction, but I didn't hold my position, made a little profit and then sold, only to see the market rally afterward.
Looking back later, it wasn't really a judgment problem, but an issue with rhythm and position sizing structure.