I think there's a certain issue that power means having to make decisions, and decisions frequently mean some gain and others lose even when the greater good is followed; plus that decisions occur within a framework of wider existing advantages and disadvantages, such that decisions not intended to be harmful may be so. In short, power means making decisions that harm people. I am not sure "harm" is the same as "abuse", however. Abuse seems to represent a sort of misuse or neglect, which is easier to avoid than harm.
One might also note Adam Smith: "This disposition to admire, and almost to worship, the rich and the powerful, and to despise, or, at least, to neglect persons of poor and mean condition, though necessary both to establish and to maintain the distinction of ranks and the order of society, is, at the same time, the great and most universal cause of the corruption of our moral sentiments."
Prime amongst this, of course, is the disposition of the rich and powerful to admire themselves. It reminds me of Trump telling a journalist "Don't talk to me that — I'm the president of the United States. Don't ever talk to the president that way." To which my answer is inclined to be "Why not?" Either don't speak to anyone that way, or you should be able speak to anyone that way. As you say, an office should not sanctify its holder, especially in the mind of its holder.
