As a general observation: notice the many ways that psychological and ideological belief systems adopted and asserted by any particular person or tribe need have no particular anchor in reality.
All belief systems possess this essentially tautological interior architecture of interdependent symbolic relationships which can so easily be entirely dissociated from demonstrable facts. This is the nature of “I believe it to be true, so it is” style of thinking, even when there is no substantive proof or support for the position: an authentic failure of executive functioning.
It is this free-floating nature of narrative or belief system(s) in a context of proliferating information over-production, of a fractured, hyper-partisan transmission medium of minds and artefacts as a cognitive burden of triage or truth-value assessment that orients minds on all sides of ideological debates towards the median or lowest-common-denominator; here raising banners and caricatures of profound ignorance.
Where information-processing and analytical thinking becomes too much to bear, people attach themselves to the simplest stories they can find, or that can find them – and there’s the rub.
The TL;DR: human beings are gullible and easily exploited.