[wrs]

I imagine that anyone who becomes POTUS is quite suddenly exposed to a whole lot of new information that might change some of their previous views. Also, in so many areas of life (management, parenting, writing device drivers) you may have strong and idealistic views from the sidelines, but once you’re responsible for actually doing it your default view becomes “it’s complicated”.

[ch4s3]

It seems more to me like having the kind of power a modern president of the US wields is inevitably going to change all but the steeliest person, and mostly for the worse.

[ncmncm]

Once you have access to classified information, you can spend literally every waking hour reading nothing but classified reports prepared for you. It can seem foolish to waste time reading anything else, which "might not be the whole story". But it puts you entirely under the thumb of whoever is preparing your reading material.

Thus, Colin Powell famously had no idea he was being played when he persuaded senators to vote for invading Iraq.