my problem is he continued it long after he couldn't win and convinced his supporters the primary was rigged against him, often focusing on state requirements that had been in place for decades, as though their singular purpose was to disadvantage him.

Even so, I was prepared to leave it all in the past until he used the GE defeat to renew the recriminations toward Clinton and other Democrats. It particularly bothers me that his supporters insist we have no right to object to or even comment on attacks on the party.
The idea that he should be able to denounce the party but citizens have no right to object or offer any view other than applause treats an elected representative treated as superior to the rest of us and thus betrays a deeply inegalitarian worldview that is antithetical to democracy and liberalism. I don't want a party that holds one man above the rest and doesn't permit the citizenry to criticize or even ask questions. They talk about the party representing the people, but they refuse to allow citizens to engage in any way other than as fans. That is not civic engagement. That so many Americans across the political spectrum take such an approach is deeply troubling to me.