Trump is as much a product of the divisiveness as a cause. People initially took a shine to him because he was a "fighter". They saw a conflict already and wanted a fully willing combatant as a surrogate.
I think it's important to keep in mind that Trump winning the primaries in 2016 was essentially a repudiation of the entire Republican incumbency by a good portion of their base.
Because basically all those arguments remain true - yet Trump didn't win. These aren't argument for why Trump would win. They were arguments for why Trump has some purchase. The reason Trump won was the elites go so sloppy they let him win, they let their garbage boogieman alternative become the choice because they were addicted to having that kind of creep as their opposition.
And Michael Moore's argument in particular is crap among these. Homeless factory workers aren't Trump's base, family construction companies are his base - I see them regularly. The well-off but not college educated.
The group dynamics of bullying are pretty straightforward. There will always be bullies at the top who want to cement their status by showing their power as a bully. To get a significant group of people to go along with the bullying, however, (think everyone laughing along when the bully makes fun of someone) that group needs to be really unsure of their place in the social hierarchy. They know bullying is wrong but at that point are somewhat terrified of ending up on the wrong side of the bullying. That's why you see so much bullying in middle school, where kids are usually just starting to find their place in the social hierarchy.
I think in the US (and many Western democracies) there is currently so much unease about economics, about finding a good, and more importantly, stable job, that the situation is ripe for a bully to come along and take advantage of people's general worries about their place in the world to think "better for me to be a bully myself than to be the person that ends up on the bottom of the totem pole". Think of the crowd laughing along when Trump mocked a reporter with cerebral palsy.
When you couple this with large, structural racial changes in the US, it's not hard to see how Trump was able to take advantage.
Hopefully Trump can accept the results sooner rather than later. His instinct to fight at all costs is not serving him well in this situation. Fortunately, it’s futile. As someone said in one of the debates, it’s not up to him whether he gets to stay, it’s up to us.
I hope the the next 4 years are more unified than the last 4.