Not everybody is a megalomaniac and if such a person got the power he wants too, he still had to convince a large group of people that he should be the leader in the holy war against the made-up enemy, as I elaborated upon
here. He would not stand a chance if the world around him reacted as Dr Spock
One could also consider that group think is the same as
herd instinct as ultimately it's groups against groups, etnic, race, nationalities, anything you can make your own group distinctive of others.
Think also about primitive survival instincts, the urge to survive as individual, to have offspring survive and have the group (species, tribe, etc) survive.
Maybe think a bit about naivity too.