There are 6*5*4= 120 cases, only one of which is that all three are white balls.

So in theory, 240 people touch it, and only 2 people can win the prize. Therefore, the profit of the stall owner is 240*2=480, the loss is 10*2=20, and the total profit is 480-20=460. That is, the stall owner can fool 460 yuan one day.