I suggest everyone actually talk to Trump supporters.Not the radical Bible thumpers who think he is the second coming of Christ, but the swing voters. Really listen to them. Ask them questions because at the end of the day the Democrats couldn't beat a crazy lunatic with the attention span of a goldfish. Things you might learn.
1. All voters are liars, and most of them feel entitled. Also most people think they are net contributors to the country.
2. The vast majority of voters oppose illegal immigration, and most oppose the level of legal immigration. They feel as if the "rules" were rigged to allow something that they never voted for. Trump will always win if immigration stays on the top of people's minds. The rigged rules belief also allows his supporters to ignore his blatant breaking of them.
3. When Trump's supporters say they want factory jobs in the Rust Belt, they don't want them for themselves; they want them for someone else to come and live in their cities and towns to pay taxes and, even more importantly, to keep their house prices up. People over 45, who own their own home, worry about the future price of their homes. Most of these people know Trump is lying to them, but the Democrats didn't offer anything better.
4. The Democrats actively alienate people. The Democrats played group politics. They claimed inclusiveness and then courted everyone but men. Every job application in the USA asks are you not white and are you not male. They alienated landlords with rent controls. They alienated builders with zone restrictions. Business owners with lax enforcement of shoplifting and homelessness. They alienated the wealthy and those with ambition of being wealthy with talk of wealth taxes. They alienated competitive female athletes with support for trans athletes. It gets hard to win an election when you have actively insulted or alienated a large portion of the population.
5. The Democrats disappoint their supporters. The Democrats claimed to support Arabs, Muslims, and in particular Palistinians but couldn't bring themselves to condemn Israel's actions. Trump loses no votes with his hate speech because no one expects anything more. Trump won the male muslim vote.
6. Voters are lazy. They don't want to understand issues. They want someone else to blame for problems and the idea that if it wasn't for group X, then the problem would be solved.
7. Voters want more government services but want someone else to pay for them. People vote based on who they think will benefit them the most personally.