What is the end purpose of power?

That is to say, why do people quest after power, at the expense of everything else, incl their own health & happiness, to say nothing of people who stand in their way?

I can't imagine wanting a billion dollars. Or dominion over a nation.

Is it an existential thing? Like, a futile flailing against mortality and finitude?

Or some libidinous pleasure in denying pleasure to others?

Or does power have a mind of its own, opportunistically hijacking human minds?