Part of these past two elections feels like it's just the hubris of the top candidates, unable to bow out or allow anyone else to stand in for them. 2016 was Clinton psyching herself up to be The First Female President and thinking that Trump was a joke (most of us did see him as a joke candidate and that'd it'd be a cakewalk). I think in Biden's case, he didn't see any other strong mainstream Dem contenders and felt he was the best shot the Dems had at beating Trump. They seem to completely ignore their progressive wing and just assume they need a centrist candidate to have a hope of winning. I just wish he'd change his VP pick, Harris is just dead weight. He needs to shake-up his campaign and pick Stacy Abrams or something (though obviously this didn't work for McCain/Palin).