I think what pisses the Demoncrats off the most is how close they came to flipping the USA to socialism.
They got Obummer care and put millions out of work, on welfare and food stamps. They almost got to Medicare (single payer) for all.
Trump comes and in less than three years turns all of this around and exposes the left for the Alinsky clones they are. He ruined their big plan and showed things could be so much better if we reject practically everything Obummer (and to a lesser extent what GW Bush) did.
They were stealing us blind (quid quo Joe is only one example) and they are truly afraid of being brought to justice.