These people systematically created a tribal political environment where facts don't matter, ridicule is the best argument, and Democrats are the enemy. They've been pounding this into the heads of any American who would listen since the late 1980s or so. Along comes Trump, who is the embodiment of all of these traits, and this extensive groundwork pays off. He's constantly wrong, but his voters have been trained to embrace that. He behaves terribly, but his voters have been trained that this is a good thing as long as the target is the left.
And of course denial of climate change, its negative consequences, and the merits of fighting it are one of the core pillars of this propaganda.
Add in the electoral college, which gives a substantial advantage to candidates who can win rural voters, and here we are.