It's called Epistemic Closure.

[BULLDOG]

I am not at all convinced that MAGA is doing "childishly bizarre behavior---in fact I have not noticed ANY MAGA BEHAVIOR ----no riots, no marches, no blocking traffic or vandalism ------what is MAGE DOING---that irritates you----I am not sure I have ever ENCOUNTERED A "MAGA"

That is the result of epistolic closure. You simply refuse to believe anything exists unless the trump cabal has already told you it exists.