It was because of their dislike of Trump, his actions, behavior, his lies, 1-6, the stolen election which wasn’t stolen and on and on.
A note of clarification.
Despite the fact I haven't seen the entire list, I am fairly certain these folks will not support nor vote for Trump because they dislike him, or his actions, his behavior, nor his lies. If they had, they would have not supported him in previous elections, but they did. Even his lies and rantings about a stolen election would not nor did it persuade any of them to not support Trump. Now don't get me wrong. They probably did not believe any of those things were qualities they admire in a candidate, but they were not deal breakers.
What was the final straw was Trump's attempted coup. These folks recognized that anyone who even thought about being a dictator for a day was definitely capable of destroying American Democracy as was clearly evidenced by the J6. It is hard to imagine anyone, let alone a former occupant of the WH, would on any day, incite a crowd to march on the Capitol in riotous fashion, and even more so on the day of certification of electoral votes. Then we learn his allies had conspired with several groups to actually lead an insurrection. And then as if not enough, Trump refused to stop the insurrection even though he had control of their actions.
Any person who would do all of that and more is not fit to be president, nor dogcatcher.
