What's going on now with non-troll democrats accepting but not being thrilled about running with Biden again is about not wanting to do the maga fascists any favors by dividing the democratic party.
Biden is the incumbent and he has been reasonably successful believe it or not, most democrats think so anyway.
So he has decided to run.
He pretty much gets the nomination even though it is true probably the majority of democrats wish he wasn't running and they could put up a new (but not a troll) credible alternative.
But another factor is that any incumbent always has a built in advantage.
A "better" younger democrat would lose that edge.
Eye on the prize is simply saving democracy from takeover by the maga fascists.