Why is the U.S. purposefully so evil? Killing your black, homeless, mentally handicapped and similar groups is not only morally deplorable no matter what crimes they supposedly did commit (or probably more often than not, didn’t commit), but also allows dictatorships and the like to argue that the U.S. isn’t morally superior to them. Which, after repeatedly seeing such cases and the rhetoric your politics are filled with, is arguably a fair argument to be made.
America is populated by people that failed statistics and embraced fundamental attribution error. Each person thinks they aren't like everyone else and even if they have the same beliefs they are extra special for having a different reason for those beliefs. The result is everyone else is an idiot and gets what they deserve.