If there is a hell where Hitler is left to burn, then which would be worse: an infinity of being torn limb from limb, as in hell, or having to forever live with the realization that you hurt someone, a person who had put their faith and trust in you to do right by them? What about taking money under the table? What about breaking a promise? What about lying? What about exercising unbridled power that causes another to lose their livelihoods or even their life?
Psychopaths need not apply for exemption. When you die, you too will feel the burn from inside your very soul and it will be worse the less you empathize in your current existence.
No, the feelings that come when you see hurt in their eyes whether now or after you die, that is the feeling you will be left with for eternity. I believe I would rather someone else administer punishment—because I can blame them for the pain—than to feel the wrath of my own conscious tearing at my soul.
I have done many things in my life that I call cringe moments (and a few damnable ones as well). A random action that I committed comes to me, usually out of the blue, and I cringe. Why did I say that? Why did I do that? Why did I not respect that person enough to refrain from my imbecilic behavior? Now think about how you would feel if you wantonly murdered, raped, and robbed?
When you die you will relive every moment of your life; not from your point of view, but from those you touched, seen and unseen, whether it is from the moment you make the transgression or the ripple of your callousness that reverberates through existence. You feel the pain, the suffering, the embarrassment, the torture you inflict. If a devil existed and he meted out your punishment, you could attribute the pain to him. With only yourself as the administer of retribution, who will you then blame?
Now, of course there is a corollary: All the love you give, all of the compassion and mercy you feel toward your fellow man will be with you for eternity as well.