My parents are scared of Sanders in some primal way they've failed to communicate. I thought I knew them better than this, but they kept this choice hidden until a few days ago. (impressive since they haven't talked to each other in years)
I'd understand them (well, mom) going for Biden - I may have done the same 4 years ago. But Bloomberg?
How does anyone listen to that much Neil Young, or believe in ineffable forest spirits, or hold what I thought was limitless respect for the decency of all humans regardless of wealth... (he, she, both)
And then they go and do this? They raised me better, I'm at a loss. And again, they did it independently.
To at least try to answer you, wierd: Buttigieg has a lot of people who may have followed Sanders, except that Buttigieg painted Sanders as an extremist on par with Bloomberg or Trump. His endorsement of Biden sent a lot of potential progressives firmly into the arms of the Liberal establishment.
Also, black voters are demographically supporting Biden over Sanders despite the last 4 years. Certain people simplify this to an Obama thing, but 538 had an interesting take that black voters are used to voting pragmatically. "Electability" is seemingly *the* issue for this election, and Biden seems more electable to many.
I may be biased since my friend group of utterly disenchanted millennials will vote for Trump's "anti establishment burn-everything" over another DNC pick - only Sanders offers them hope at all. They don't even like Warren, which I think is... telling, but whatever. They are the actual Bernie Bros, I guess. Almost entirely disengaged, consuming a wild arrangement of conspiracy theories (from Coronavirus to Alex Jones) and utterly without faith in our leadership. Broken.
Whereas I don't know if I'll vote for Biden over Trump. I might. But if the DNC superdelegates force it, then I too will literally watch the world burn for their hubris. Doesn't really matter what I choose at that point, so I might as well vote third party and stock up on liquor.