I see it as an extension of the myth of American purity and external corruption. “This person is evil, some outside power must have compromising info on them.” “Immigrants are violent criminals preying on innocent americans.”

These attitudes ignore the reality that bad people can come from anywhere. There are plenty of villians with very mundane origin stories. What matters is if everyone else has the will and ability to keep bad people in check and hold them accountable.

The grifters in charge need no other motivation than a sense of superiority and an opportunity to make a buck.