I think you are forgetting one trait the humans have (this has also been observed in several animal species)...empathy. Without it we would all be sociopaths. The fact that we can put ourselves in someone else's shoes is the main reason that we do not act like greedy bastards every day of our lives.

Of course there are individuals who lack empathy and those are the ones that gravitate to activities where they can act out their disfunction such as law enforcement, the military, politics or CEO's.

I don't know about anyone else but I don't go about my day supressing any impulses to screw over my neighbors just because I am fearful of the consequences...the thought doesn't even cross my mind.