"Such people don’t seem to exist — at least in large social blocs — anywhere else in the world."

I would look at England's North, where the majority of people still apparently believe in the wealth and happiness that will accrue to them from Brexit; to Israel, where the majority apparently believe in the legitimacy of slow genocide of Palestinians; or at Turkey, and the right wing parties in France, Greece, Spain, Italy, and Germany.

Self-centeredness has been taught in the USA since Freud's nephew Edward Bernays taught advertizing techniques and invented public relations in the beginning of the 20th century. See The Century of the Self. https://www.youtube.com/watch?v=DnPmg0R1M04&ab_channel=JustAdamCurtis.