When I see that the family next door gets robbed, raped and murdered, I do what I can to help them. This is not only in their but also in my interest, because then I may reasonably expect that the society would also help my own family should they have to experience the same hell. I don't want to live in a world where someone can commit the worst crimes and no one cares because "it is not in their interest". I guess that's part of what is called civilization.