What is the probability of winning at craps?

The odds are set so that the longer you play, the more probable it is you will lose. Its like betting on a jar with a thousand marbles in it. 600 of the marbles are black and 400 are white. You bet $1 each time a marble is picked and your bet is that a white marble will be picked. If a white marble is picked, you get your $1 back plus an additional $1. As the marbles are being picked, you may be winning at times but ultimately you will lose $200 because there are 200 more black marbles than white marbles. This may seem very simplistic but it is exactly what happens when you play craps.