Is it right or wrong for predators to kill? Why are they so mean and make others suffer like hell?

You can't just assume that everybody knows what you are talking about, you have to explain your question. I guess you are talking about wild animals. Wild animals don't observe religion. They learn from Mama how to find food, and the kind of food they eat depends on their digestive tract. A cat's gut is much shorter than a dog's so a cat can eat only a small list of vegetables, but a dog can have more variety. Any animal that has incisor teeth (fangs) MUST eat meat to maintain health.

Only humans make up baloney about how nasty it is to eat meat. The fact is humans have incisors (fangs) and a strict vegetarian eventually becomes a sick vegetarian, regardless of your philosophies. My religion plainly says "Rise, kill and eat!"