I think the mysterious "they" that runs the DNC always knew that Biden was going to be a loser, but they felt confident that they could either drag him over the line or keep it close enough to claim that the election was stolen and keep that going for another four years.
If they're actually getting panicked it is, I think, because it's getting very possible that not only could Biden lose, but he could lose by a margin outside the realms of claimed cheating.
If they don't have the "Trump cheated" story going, they'll actually have to come to terms with blowing the presidential election in 2016 and failing to unseat Trump in the subsequent coup efforts. This fantasy land where they have been living in where Trump isn't a duly elected President who actually won by playing by the rules is going to collapse their reality. They don't want to live in a country with citizens who vote for Trump in the first place, much less one where a candidate like Trump could be sufficiently popular that he could win a majority of electoral votes or heaven forbid even the national popular vote.
I predict Trump will win the national popular vote this time.
He will get “unexpected” votes from:
Hispanics in California;
Jews in New York;
Catholics;
Blacks (men, not women);
Ex-Democrats in Washington, Oregon, Chicago, and elsewhere.
But he won’t get many votes from the snooty liberals in places like Mount Lebanon, a suburb of Pittsburgh.