Little to none.

I wholeheartedly agree with your proposals of fact in your post to greenfly, 'n can to a large degree document this. I also disagree with Kero's response in entirety.

...but the fact that what passes for "happiness" as far as they will ever know it is trying to hurt other people for no reason, well... you're right, it makes them evil... but it also makes them pathetic. Stunted little beings who are their own greatest obstacle towards any sort of joy or fulfillment...

I don't need to hate them to put a bullet in the agressor. I need merely have a clear sense of moral duty and an understanding of vehement defense against active agression. 'n I don't need to hate to be happy... I'm better off without it. 'n last but not least... it's hard to hate someone for having extremely self-destructive tendancies, when you could just pity them for being a sad, stunted little reject of natural selection who is destroying their life all on their own.

Pity is more relevant. As is focusing on where the world can be changed for the better. You're not exactly going to save them from sending their life spiraling down in flames, and their self-destructive tendancies might just help their intended victims, so why not save an endangered species or something? It'd give you something constructive to do with your time...