Because they're sick of establishment's wars all over the world.
But insulting of Khan family was dumbest thing Trump ever did.
Khan put himself in the political arena. Anyone who does that is fair game for a rebuttal. And Trump went fairly easy on him, by Trump standards.
I was unaware that questioning a gold star parent's loyalties, attempting to string him together with the group that killed his own son was going "fairly easy."
Trump does not rebuttal. That requires careful thought and concise language. He just throws tantrums at people he doesn't like for the things they say about him regardless of their standing or the quality of their criticisms.