Because the media has taught these people to form their entire identity around their politics and they will protect themselves tooth and nail. To attack what they believe to be normal is to attack them personally and they respond by withdrawing into their shell like a turtle when they perceive a threat.

They could bring a kid out on live TV, kicking and screaming, onto the House floor as the pedovores circle to feed, and these people would refuse to watch the video chanting "CONTEXT IS IMPORTANT." "UNTIL I SEE IT ON CNN IT DIDN'T HAPPEN" "YEAH BUT TRUMP--"

Some of them are, sadly, beyond being helped.