Perhaps the very traits that drive and enable a person to climb to the top, in terms of personality ... are the ones that give this same person a need to be powerful, to stand out, to have the lectern, etc....

And ... power can easily corrupt a person, or give them illusions and delusions. Power is addictive. So then, the person, is an ever increasing need to maintain and expand his/her power, fears any competition. And of course, he/she also needs to demonstrate and use that power.

And thus you get warping of the personality, and the person falls into the trap of being a bully.... Unless, the bully was inside all the time, and climbed due to traits in the bully personality, and now, having reached power, oh boy! Sort of "Apres moi le deluge!" And the bully rules.

Too bad for those "underneath" the bully. For... They will pay the price.