Winston Groom said this quote

So the next day I asked Dan how is it that Bubba can get killed, and what kind of half assed nature law would allow that. He thought about it for a while, and said, 'Well, I'll tell you, Forrest, all of these laws are not specially pleasing to us. But there is laws nonetheless. Like when a tiger pounce on a monkey in the jungle - bad for the money, but good for the tiger. That is just the way it is.