Correct, the Tea Party is not the same thing. Movements like that can fizzle out without a figurehead.
A better comparison is the situation with Bernie Sanders in 2016. A lot of those voters felt cheated and sat out the election, or voted Jill Stein in protest. But Sanders mitigated much of that damage by throwing his support behind Clinton, and later Biden.
Trump will never "realize it's over and that will be that". He will go to his grave screaming about how this election was stolen from him. There will be no swallowing pride, being the bigger man, and doing his best to help the GOP in the wake of his defeat. He's taking his ball and going home. And he's taking millions of diehard followers with him. He may have even opened their eyes to the GOP establishment being "the swamp". Even sidedish is redpilled now!