Sometimes even players know a lot about self-control because they've read a lot of information on forums or from professional players, but they still can't control themselves because they constantly lose their cool and make various in-game moves they shouldn't. The problem is, they're paralyzed, giving themselves a chance to place a bet, and then another, hoping to smooth out losses, and so on. This is a complete lack of self-discipline. I don't allow myself to do this, because I've learned to immediately turn off the game as soon as I realize I've had enough for the day.