I'm starting to think that the DNC picked the two worst they could offer in Biden/Harris cause they know they can't beat Trump aside from massive cheating. In a sense, they spared the rest of their viable pool(even Sanders) by pulling them out and pushing to two least likely to make a dent against the silent majority. If Biden wins, golly, they get carte blanc. If Biden looses, they just have to survive four years while building up Warren or some new option who can with favor from the left.

Though, I doubt the left is able to hold together such a long term plan. So long as Trump doesn't piss off the republicans too much, he'll have lame duck authority. It may be better for the left to lose the election in the short term and long term, as Trump in lame duck mode will be their biggest threat. The gloves aren't even close to coming off yet.

Maybe that's their chaotic psyche. They know Trump will burn them if pressed to. He has the keys and can turn them. For now though, he's offering them the mercy of keeping the process constitutional.