“Because he is polarizing.”
O.K. Fair enough
“And the polarization got worse from 2016 to 2020.”
And that’s where your premise faulters. Trump became less polarizing between 2016 and 2020 because he had a record of sucess that he didn’t have in 2016. He gained support among independents, and in particular Blacks and Latinos between 2016 and 2020.
Trump didn’t cause the division, he revealed it.
You do realize that the things that conservatives consider "successes" - the tax reform bill, tightening the border, Supreme Court appointments, etc., greatly pissed off people who didn't like those things. That's what it means to be polarizing - you attract both more friends and more enemies.
He gained support among independents, and in particular Blacks and Latinos between 2016 and 2020. Yes, but those groups still went for Democrats overall, and more of them voted in 2020 than in 2016. The Democratic get out the vote drives in the ghettos and barrios was incredible.
He lost some votes of Soccer Moms in the suburbs of Atlanta, Milwaukee, Philadelphia and Phoenix. Right there, that's the election. It didn't matter if Trump was able to get more votes from the Minorities. Right now, he's not going to get the votes of the same bloc in 2024. They hated Hillary so they voted Trump over Hillary. That was not the case in 2020.