It's an interesting point, I don't think that's it completely. I do think it's something to with my tolerance and acceptance of risk and the emotional adrenaline that comes with not being in control of either being very poor or very rich. I think Lucien Freud (a terrible gambler) once talked about it being pointless unless your risking true loss, as the emotional spectrum doesn't get the full experience. The fact that it usually happens when I'm bored or drunk alone might make it more likely to be true.