You can make yourself feel better about yourself if you project your shadow side, if you project your own potential for evil onto someone else. By annihilating them and, therefore, your shadow, you bring yourself into some state of purity or reformation.
“You know, now it's sinking in. It's taken me a long time to realize - and it is sinking in - how important this book is. And I have a certain distance now. I've done it such a long time ago.”