People needed a thing to hate, the media gave them a thing to hate.
It worked *too* well though, and now the rifts they caused can't be undone, despite Joe's best efforts. That hating half (really more like 1/3,probably less, the breakdown is ~1/3 Dem, 1/3 Repub/ 1/3 independent) want to see the other (hated) half punished, ostracized, and socially exiled. The media convinced them Trump's a White Supremacist and therefore anyone who voted/supported him must also be. So now they're making essentially "enemy" lists.
So they won't be interested in even trying to get along. or there won't be enough willing to do so. On the other side, the "hated" folks are pissed at being called uneducated white supremacists/racists for 4 years, so what people on the other side are left and do want to try and repair things...well they'll get told to fuck off.
We're fucked is what I'm saying. Historically whenever you get an irreparably polarized population, you get copious amounts of bloodshed.