The saying that power corrupts and absolute power corrupts absolutely, is very correct, because the desire to control others is part of human nature. Everybody is humble until you put them in power or they rise to position of power, this is when that part of human nature that tends to control others will begin to manifest. And as absolute power is atained, the desire to control will become absolute, anybody that stands in the way becomes an enemy that should be crushed. It'll take great efforts and high discipline to do away with this natural desire to control.

One of the reasons why you'll agree that it's human nature to control others is where you have a powerful leader that controls his subjects, his subordinates will have the desire to usurp him and take over power to continue  the control of others. Even the critics of the regime, when given the opportunity to be in power might be worse off than their predecessor. So it takes exceptional integrity to be in power and not abuse it.