It makes me wonder if Monty had some kind of personality disorder. The man seemed utterly unaware of the consequences of his actions on others.
Lust for power, the same "disorder that all of us have. One could speculate on varied things like overcompensation for an inadequate penis, hunger for acclaim, lack of parental affirmation, etc., but there's no point. Lust for power is universally the human condition--he just had an opportunity that few others do and decided to go for it.