Great question, and well phrased. It's refreshing to see a few people in this thread with a genuine interest in trying to understand the root causes instead of engaging in personal attacks and emotional appeals.

I found it helpful to go directly to commentators on the right for deeper analysis. The average Trump voter generally has a hard time articulating specific reasons. Same is true on the left. Not to say they don't have valid reasons for their votes, but it's difficult for most people to remove the emotion online and clearly articulate substantive reasons.

This really requires a much longer essay. I found it helpful to set aside the impulse to immediately say "yes, but Trump did the same thing but worse." For the sake of brevity, the below focuses on the Democrat's mistakes which I believe were the ultimate root issue.

The summary of my analysis so far:

Trump rose to political fame in 2008 off the ridiculous "birther" claims against Obama. The left saw his success and has been trying (and failing) to beat him at this new media race to the bottom game. The Democratic party has strayed way too far from the center over the past few years. Kamala was the most progressive (far left) Democrat candidate in the history of the US. She ran a short campaign with many critical mistakes.

Because Kamala never clearly articulated her plan for the country, this left a lot of undecided Americans feeling like she was being controlled by the Democrat leaders and potentially hiding plans for overly unpopular (by majority) progressive policies. Specifically the plan to tax unrealized capital gains. She also made many of the same mistakes of Hillary Clinton's campaign assuming white women and black males would vote for her because of identity politics instead of winning them over on her policies. The right and center voters are extremely tired of being talked down to and lumped into identity politics.

In the end, Trump's campaign did a better job swinging back to the center while Harris's campaign left a lot of open questions on the table. This is a well documented mistake in American election political history. It almost always costs the win in a close election. Perception is everything. An ultimately the critical mass votes on policies and plans (whether real or perceived) vs character.

Why did Trump supporters ignore his atrocious behavior? They didn't, at least not completely. Mostly, the left's insane tactics of trying to equate Trump to Hitler using out of context sound bites backfired. There was a tremendous amount of social media activity on the right countering every one of these attacks using the source material from Trump's speeches. It made the left and mainstream media untrustworthy. All Trump had to do was pull back from using the same tactics (which the right uses just as much as the left) a couple months ahead of the election. This allowed the left to dig their own grave with undecided voters. Notice Trump stopped (or substantially reduced) using nicknames and personal attacks on Kamala many weeks ago.

Given that the right and most of the center lost all trust in mainstream media, it made it easier for people to rationalize. "Yes, Trump is morally bankrupt, but we had 4 pretty good years under his previous presidency. So I'll vote on the issues and not character."

And issues for most Americans always comes back to economy and taxes.

The short of it: Democrats lost the election more than Trump won.

Here are some videos that dive deeper into the analysis.

Piers Morgan - see Cenk Uygur's (Democrat) critique of the left. He's been highly critical of the way Democrats are playing politics for many years.

https://youtu.be/mIDLJnKesQM?si=tQu_H_JMqSLFVTNb&t=263

Konstatin Kisin - 10 reasons Trump won - simplified explanation for non-US citizens.

https://www.youtube.com/watch?v=KlFTLhei7J8

Winston Marshal - ignore the "libtard" and gloating; Winston has been ruthlessly attacked by the left for years and this video is not his normal tone; pay attention to the examples of where the left used Trump soundbites out of context to try to paint him as the next Hitler

https://youtu.be/d254zOhdEA8?si=F9WQV0f1xGlZEkqw&t=85

Kevin O'leary on Fox News - talks about why small business owners voted for Trump due to fears Kamala would tax unrealized capital gains

https://youtu.be/7sNH_6eha9Y?si=2OuqyzukvSr4_nvg&t=81