They still win.
If it cost $5 to try, the prizes are worth $5 for them to buy in bulk.
With carnival, it isn't all about the prize but the aspect of winning. To be able to hold your top prize and to carry it around with you is a way to show off to the world that you are a born winner. Makes a kid feels special. Makes the guy who spent over $100 just to get his date a prize feeling special.
I still like my low maintenance country girl. She can talk you out of everything. Saves me money and all that implication that comes with the carnival world.