*warning: this post is not well explained.  I know what I mean, but it's a slippery philosophical concept and I'm struggling to put it into words.  So if I've offended you, please ask for clarification before you flame my bum off*

I think I understand how this supremacist thinkging comes about.  If you've had (or perceive that you've had) someone telling you you're less important, defective, whatever, this philosophy can evolve as a defence mechanism.  The person learns to discount others' opinions, because those opinions are so damaging.  So, they do so on the basis of "why should I care what you think of me, because you're inferior.  You're not better than me because I'm better than you."

It's so sad, because then the hated becomes the hater and the cycle continues.  And they're trapped into perpetuating the very theory that hurt them in the first place - the idea that some people have more right to exist than others.