Robert Cormier said this quote

You see Carter, people are two things: greedy and cruel. So we have a perfect set-up here. The greed part - a kid pays a buck for a chance to win a hundred. Plus fifty boxes of chocolates. The cruel part - watching two guys hitting each other, maybe hurting each other, while they're safe in the bleachers. That's why it works, Carter, because we're all bastards.