"It is difficult for men in high office to avoid the malady of self-delusion," Coolidge wrote."They are always surrounded by worshipers. They are constantly, and for the most part sincerely, assured of their greatness. They live in an artificial atmosphere of adulation and exaltation which sooner or later impairs their judgment."

Longer excerpt here:

Coolidge made remarks around this time, which would benefit anyone holding high office to consider...."It is also difficult for men in high office to avoid the malady of self-delusion. They are surrounded by worshippers... They live in an artificial atmosphere of adulation and exaltation, which sooner or later impairs their judgment. They are in grave danger of becoming arrogant or careless... the chances of having wise and faithful public service are increased by a change in presidential office after a moderate length of time... It's also a pretty good idea to get out when they still want you."

The system we've got for determining control over nuclear weapons and history's most powerful military already pre-selects for odd characters. Few of us would want to spend two or more years riding a bus around Iowa mouthing platitudes to people we've never met, and scrupulously self-censoring to avoid"gaffes," which Michael Kinsley famously defined as when a politician accidently tells the truth. Even fewer of us are so suffused with a sense of our own grandeur that we'd feel up to the job. I remember my first visit to Little Rock, Arkansas, which is distinctly less impressive than Red Bank, New Jersey, near where I grew up. Bill Clinton imagining he could be president struck me as about as outlandish as the mayor of Red Bank thinking he could be"Leader of the Free World."

If and when that sort of insane ambition actually pays off, and you win the presidency, it would be hard to avoid thinking you'd been touched by God, even if you aren't religious. Add to that the social environment the president moves in, where he's surrounded by people who treat him like a god and insulated from people who'll tell him he's full of crap. (It's probably worse if you don't read newspapers and the Secret Service cordons off protestors beyond your line of sight). I wrote more about this here, with just as little insight into what can be done about it.