Because every one of America's systems is designed to create a population of people who don't think for themselves.
Education is still designed to teach students how to be factory workers, critical thinking isn't taught. Universities turned into corporations and plummet graduates into insurmountable debt to keep them from actually participating in the economy to prevent any real change from happening.
For decades, Sex, religion, and politics have been deemed improper conversations and should be avoided at all costs. The result is no one knows how to have conversations about difficult topics. More, conversations aren't possible because we've been flooded with confirmation bias and the belief that disagreements are considered personal attacks.
We've been lulled into a false sense of security for years, and have been flooded with enough media and advertisements to make people believe real-world problems aren't real problems unless it affects the individual. Even then, those who suffer are gas-lighted into thinking they're the ones at fault.
This isn't a trump problem, he's just lit the flames of a pyre that's been built. The government has done everything it can in the last 50+ years to breed a society of people who only care about themselves, their convenience, and who will always trust authority with no questions asked because as mentioned before, questions are seen as an insult to intelligence rather than a way to learn and grow.
The best prisons are the ones where the inmates don’t know they’re in it.