WHY doe the Inner-Party want POWER?

Towards the beginning of the novel, Winston says 'I understand how; but I do not understand why'

This question plagued me during the entire book. Why does the Inner-Party or the higher-up oligarchy want to run the Big Brother system? What is in it for them?

Towards the end O'Brian claims that the inner-party oligarchy wants power for the sake of power. That power is an END and not a means.

Why do they want complete and utter power over people? Why put them through Room 101, why have helpless obsequious party-members running around.

Why not just kill everyone off and live with with all the wealth? O'Brian says that 'they' are not doing it for opulence. But then again, 'they' get no glory for their power.

Is it really that fulfilling to watch people be idiotic (proles), or watch people be fearful and dutiful (outer-party)?

I still no not understand WHY.

I think part of it is just because they want power, for the sake of power like O'Brian says. Also, the Inner-Party members could be no more aware of the truth of their society than the Outer-Party or the proles. If everything is all controlled by one 'Big Brother' at the head, then they could be just as brainwashed.

If they killed off all the proles, then they would have nobody to get them resources, etc.