How do you know that Karma doesn't exist? I think that Karma is a great coping mechanism for dealing with bad things that happen to us. I think that it's also a good philosophy for doing the right thing.

If more people believed in Karma, I believe the world would be better. Since none of us know about the afterlife, parallel universes, curses, or millions of other things, I can confidently say that you are unable to prove that Karma doesn't exist.