People who end up in positions of power tend, with few exceptions, to have large egos. With this comes a sense of special privilege. As a maker and enforcer of rules, it’s easy to see one’s self as not being subject to them. Someone holding the stick is less likely to fear the stick.
Add to this the fact that power is only an abstraction until it’s exercised. You know you have power when you make people do what they would not otherwise want to do—pay a bribe, perform a sex act, contribute to your campaign, hire your nephew. Orwell makes this point well in “1984”:
“How does one man assert his power over another, Winston?”
Winston thought. “By making him suffer,” he said.
“Exactly. By making him suffer. Obedience is not enough. Unless he is suffering, how can you be sure that he is obeying your will and not his own? Power is in inflicting pain and humiliation.”