I promise, it's mostly indoctrination/Cold War cultural osmosis, and the stupidity is merely secondary if it's even present. This shit gets actively drilled into most USonians from early childhood and has to be consciously unlearned by anyone who isn't Black or Indigenous. Often it takes coming to a university or workplace with a lot of non-US citizens and spending years listening to perspectives of people coming from many other parts of the world to even notice their own ideology and biases, never mind making the conscious decision to reject the shittiest parts of US culture and ideology. This is of course one of the reasons why reactionaries hate universities for "turning" their kids into socialists and progressives, and why the US immigration enforcement infrastructure actively screens out would-be immigrants they think might be too "subversive". Somehow even the most neoliberal and boot-lickingest grad students on visas manage to effortlessly or even accidentally punch multiple holes in the US exceptionalism worldview just through a few minutes of casual conversation about economics, healthcare, or geopolitics, because the US is just that deranged for those looking in from the outside.