Power does not corrupt. Throughout history there have been individuals who used their power to do extraordinary good.
What power does do, specifically power that is hierarchical in structure, is attract those who are already corrupt. Those individuals crave power above all else and will do anything to secure that power for themselves whereas someone who would use that power for good would not resort to underhanded tactics in order to manipulate a win and is thus less likely to succeed in obtaining that position. This is especially true in our electoralist system where the method in which people obtain seats of power is nothing more than a popularity contest.