I think there is a couple of factors when you are playing someone for money. The money on the line is usually more substantial when you are gambling. Also, I feel it is easier to bear down when you are going against one opponent, as opposed to going through a field of players. In a tournament, you might sit between matches which can cool your stroke too. Oh, and there is instant gratification when gambling...when you finish your race to whatever, you either lose or win the money. In a tourney, you just move on to the next match.