I don't believe that all men are created equal therefore I do not ascribe to the notion that we are all capable of being as heinous as Hitler, Stalin, Netanyahu, Etc.

I think most people feel this way.
But to be precise, humans, I would even go as far as to say most humans, will behave as monsters given the wrong circumstances, but how far they will go varies widely. It is very shallow and simplistic to think everyone will be the same given the circumstances.
To be absolutely and completely corrupt and ruthless is not easy. You have to train for that. The more you act like a monster the more of a monster you become. Nobody starts out as a serial killer. You start with small animals, torturing and killing them, you move up to cats, dogs, become a bully, play cruel jokes; by your monstrous acts you grow more and more callous, and eventually, you attain a level few dare to go. That's what gets you a Saddam Hussein or a Mao. And because I believe in a sort of Yin and Yang in life, just as there are truly evil people in this world, there are truly good people in this world and people like joswift insults and dishonors these imperfect saints of the world but lumping them all together with the truly evil and that's only "circumstances" that determines this.
"Very few people can be totally ruthless. It isn't easy."
Even the ruthless murderer Tony Montana had a line he will not cross. Not everybody is as cold, cruel and barbaric given the "right" circumstances as joswift will have you believe.