Bernie lost because young people didn't come out and vote for him this time around. Nor did as many other people. I think his mandatory public healthcare scared the shit out of a lot of people. At least that's the consensus among Dems I know that voted for Biden.
Were there any other candidates that stood out as big accomplishers in the field? Maybe Bloomberg but he was super hatable everyone was meh or so vanilla you couldn’t put them on any side of any issue.