Being impervious to facts,  is simply part of Trump's attraction to his base. Factual facts get in the way of Trump's need to tapp (using his spelling) into the irrational fears and prejudices of his supporters.

I sincerely hope that I'm proven wrong, but Trump's approach to making America safer by an indiscriminate ban on Muslims from a handful of countries that have produced relatively few terrorists will risk the radicalization of many otherwise reasonable people who now feel threatened and marginalized. I listened to an excellent interview with an Iraqi-American doctor, now living in rural Georgia and a former interpreter for US troops in Iraq. Since Trump's election he and his family have been taunted by his patients and their neighbours to the point that they are picking up and moving to California. It is doubly tragic since doctors are hard to come by in rural Georgia; and his teenage kids, born in America, are now ideal breeding ground for terrorist indoctrination. So sad.