alt Hacker NewsThe key point is not what they have done (too many examples of bad behavior to list.)
The key point is how they see themselves. The average American sees the US as "the good guys". This is not a self-image lightly over-turned. Regardless of how the rest of the world views them.
This is subjective, but I think this image wasn't uncommon in US-aligned countries either, but at least this seems to have changed in the last decade or so.