1. to beat a monster like Trump, who is an incumbent, who survived as a scandal he can spin as persecution, with a base that rightfully deserves all of the scolds and scorn that so-called "Bernie Bros" receive, will require massive turnout, massive discipline, and no voter left behind. this is already made difficult by the entrenchment of voter suppression and disenfranchisement put in place by the GOP after the Supreme Court frisbeed the Voting Rights Act, in reaction to Obama actually working his ass off to win in 2008. that's why you saw people waiting 7 hours to cast a vote.

2. there is a fundamental, substantive divide (and people don't wanna hear it, but Obama's admin has a lot to do with this) within the group that typically votes and would be convinced to vote Democratic. simply, it's this: people who are just OK with the President being a Democrat vs. people who would prefer that over the GOP hellions, but actually care about what happens afterward. bridging that gap is difficult enough, but then...

3. ...Joe Biden offers NO vision of the future, immediate or otherwise. he didn't even have a coherent message going into the SC primary. no one knows why he's running except he's gonna replace Trump. with regard to the divide in #2, that's fine with the "Get Trump Out" contingent, but the rest, who would be required to actually Get Trump Out? would be skeptical or worse, apathetic. Joe's record of shoddy bipartisanship, which would be known in the "we care" group, would not inspire.

to make matters worse, his public demeanor suggests he may not be up to snuff to actually make the kind of decisions that would change those people's minds.

4. Sanders has much of the "we care" group on lock, because he does offer a vision of the future and is speaking directly to the material needs of the people who support him. Including "Getting Donald Trump Out". The mass media tends to obscure that in favor of painting him as "selling socialism". surprisingly he has a HUGE contingency among Latino voters, where Biden is completely weak. Those numbers would be also needed to "Get Trump Out". the crossover if Biden is the nominee can't be confirmed to be 100%.

The Democratic decided to unite around the possibly worst candidate they had left out of their bag of tricks. Kamala Harris, who was weak in a number of different ways, would have least have had a "sound mind" on her side. Elizabeth Warren would have had "party-approved progressivism" on her side. Julian Castro would have inspired. Instead, the DNC boosted the most right wing candidates they could and settled on Biden immediately after South Carolina.

unless he avoids the spotlight or actually puts together a vision plan that HE INTENDS TO ENACT AS PRESIDENT....

it's gonna be a lot of "Sleepy Joe" jokes onward to Trump's reelection.