Eh, I think hiring someone else to run your company /without any supervision/ then expecting them to act in your (the shareholders) interest rather than their own is irrational.

Really, setting any employee in a zero accountability situation and expecting them to act in your interest is irrational... but when the worst an employee can do is hang out on facebook all day rather than working, it's not as big of a deal as the executives who can line their own pockets with much more of your money than most employees take home. Executives can and do take home all kinds of rebates, vacations, and other goodies from vendors.

so yeah, I think the behavior of your typical executive has very little to do with what he or she believes is the best interest of the company.