I think they have TWO major fears.
Of course they're afraid of losing their power, but just as importantly, they're panic-stricken over the knowledge that ANOTHER successful 4 years of Trump will prove to the country exactly how Democrat policies have damaged the country, and will likely lay the groundwork for at least one more term of a Republican presidency, and quite possibly more. And the Democrat fossils living in Congress like Pelosi, Schumer, Blumenthal, Bernie, Clyburn, Hoyer, Pascrell and Maxine Waters will likely all be pushing up daisies when the dust settles.
And we'll never see a prettier sight!