This is both (1) not necessarily true -- there's no first-principles reason why being powerful implies being unethical -- and (2) deeply pessimistic and defeatist. You can apply whataboutism and say that everyone's equally bad, but I assure you that there's a pretty big difference, even down to your quality life, between the types of systems you choose to participate in.

It's not pessimistic or defeatist; you first have to recognize the limitations and failure modes of your system before you can think about changing it.

Is it possible to live in a world where powerful entities have gotten there through ethical means? Sure. We don't live in that world, though.

And yes, if I said "name me one powerful person/entity that got there through ethical means", I'm sure you could give me a name. But that name would surely be an outlier.