I think it's pathetic that one of the largest genocides ever was caused because of a crazy conspiracy theory. Hitler had a belief that people with blonde hair, blue eyes and fair skin was the supreme form of a human being. He called them the "aryans" and he believed that the reason aryans couldn't come to power was because of the Jews.
He believed the Jews had a secret conspiracy formed just to keep the aryan race from flourishing. This is just absolutely crazy and it's pathetic to think that a human would kill so many people over something like this.
Bamfzilla, I'd also recommend on reading up on the German philosopher Friedrich Nietzsche. A lot of things Hitler believed in have similar ties to Nietzsches views. Might give you even a bigger perspective on the things mentioned in Mein Kampf.