American Exceptionalism: the Good and the Bad

Robin Hanson says after citing research showing that people are more willing to do bad if they've recently done good:

Citizens of the United States are especially proud of a history of (supposedly) doing good. The US sees itself as having saved the world from Nazism and Communism, of creating and sustaining modern medicine, of educating the world via the best universities, of being the main innovators in computer tech, of upholding the highest standards of civil and gender rights, of being unusually devoted to religion, etc.
All this self-respect, deserved or not, probably makes US citizens more willing to do bad, both individually and collectively. Dear US citizens: please ask yourself how sure you can be that your actions on the world stage are actually for good.