Unlike life in popular fiction...
Nobody ever sees him/herself as an evil bad guy.
It's always "I'm the Good Guy, everyone that opposes me is Evil!"
Ah hell, This explains it better than I can:
http://mrmagundi.wordpress.com/2013/01/30/on-goodness-and-niceness/
"‘It’s more important to be good than to be nice’ neatly summarizes the beliefs of Pol Pot, of Robespierre, of nearly every terrorist there ever was; and I’m sure that, translated into Latin, it was the official motto of the Spanish Inquisition. All the misery in the world is caused by people hell-bent on being good at all costs.”