No. That was point:
2) Sometimes the guy at the top doesn't have the best interests of the country in mind, and nobody can make him.
If you want to call that corruption you can. In my mind it merely includes corruption.
FWIW, I don't think that power corrupts, rather it's lack of consequences. This is closely related, but not the same. But it's also true that power attracts the corruptible (as a gradient). Different people are corruptible in different ways and to different degrees. And one consequence of that is that they are attracted in differing amounts to different kinds of power. The guy who's attracted to being a policeman isn't the same as the guy who's attracted to being a politician, and neither is the same as the guy attracted to being a banker.
P.S.: Yes, that's still an oversimplification. Think of it as a finger pointing at the moon. Look at the moon, not the finger.