"In my opinion, anybody able to convince another human being they are worth $40 million a year -- and keep a straight face while doing it -- is worth every penny."
They have to convince a committee.
A committee is a life form with six or more legs and no brain. ROBERT HEINLEIN
Actually the compensation consultant has to convince the committee.
But the idea is very simple -- someone/anyone's salary is tied to the amount of money they can make for the person they're working for, whether that be a single individual or a bunch of stockholders. If I'm putting up dry wall and I bring in six new jobs to the guy I work for, then I expect to be compensated for my trouble. If I'm a CEO and I add a couple hundred million in value to the company, then the board better pay up.
The people who complain about CEO salaries are almost always those who have no concept of this principle, neither do they typically add value to the company they work for -- what they do is do their jobs and add no value to the firm.