On staying within your circle of competence

In his far from mediocre book Risk Intelligence, Dylan Evans describes a professional backgammon player by the name of J.P. “He would make a few deliberate mistakes to see how well his opponent would exploit them. If the other guy played well, J.P. would stop playing. That way, he wouldn’t throw good money after bad. In other words, J.P. know something that most gamblers don’t: he knew when not to bet.” He knew which opponents would force him out of his circle of competence, and he learned to avoid them.

Excerpt from: The Art of the Good Life: Clear Thinking for Business and a Better Life by Rolf Dobelli.