But you have to understand, the shift of manufacturing from the US has just devastated the economies of entire regions. You have children fleeing where their families have lived for generations. I'm convinced a factor in opiates getting a toehold in these areas was due to people going on disability to try to stay economically afloat, and getting prescribed painkillers as cover for faked injuries or in recovery for real but unneccessary surgeries (I have no proof, just anecdata).
US hegemony was good for them. It helped payed their mortgages and their kids' tuitions. It's easy to magnanimous when you aren't the one losing your house or kids aren't ODing from fentanyl. And the resentment is real when you see new grads at Google or Facebook making 10 times what you make, or CEOs making 1000 times what you make.
edit: the president did little, if anything to help their situation and channeled that resentment for his own benefit. It is a matter of national security that we all fix this and I hope the new administration will prioritize it.