But they're not. Instead it's brilliance and success. The following reasons are in no order of importance. Because if everyone acted this way we'd live in a beautiful world. And the overwhelming majority usually indicate that most of their suffering has come from people.
People hurt people.
Reason two to be good. Because you will like yourself more. When you do esteemable things, you have self-esteem. Reason three for why be good. Because you will probably be treated better.