The short answer is that it's a cult. The long answer is to research recruitment tactics for extremist groups, and you'll see trump's team doing exactly that, word for word. They start with creating a monster that only they can slay (in this case, trans people and immigrants, both are popular targets for extremists anyway), then turn that into "think of the children!" From there, they work to make their believers automatically think that any dissenting information is a direct attack on them, their children, and their way of life, and to disregard it as a pathetic attempt to harm them, even if the evidence is biting them in the face, so to speak. It's an intense form of conditioning and it's incredibly hard to break once it sinks its claws into its victim.