The act of nurturing within you and others the belief that you are exceptional and all others are inferior. Entire political strategies have been built on this concept, for instance, Trumpism. Trumpism is the firm belief that adherents are superior in thought and deed to opponents, especially ones of color and minority status. You aren't born with this abhorrent belief, it has to be nurtured either by you or with your consent. The irony is that people who hold firmly to a belief in nurtured exceptionalism are by definition unexceptional as human beings.
The Proud Boys created a platform of nurtured exceptionalism, using the power of social media to propagate a cancel culture to target minorities and those with beliefs opposed to theirs.