Progressives and voters who would have normally voted Democratic but ran to third parties in 2016 were absolutely to blame for HRC's loss to Trump! I think most people learned that purity politics is a fraught endeavor, given what resulted with the Trump administration.

Biden won't lose to Trump 2.0 unless those same voters react the same way as they did in 2016.

As I have mentioned before, challenges to a sitting president seeking a second term inevitably weaken the incumbent and usually cost them the election as happened with Reagan v Ford and Kennedy v Carter. (Yes other issues were at play, but the point still stands).

Biden was not my first choice in 2020, but swapping candidates at this point is politically counter productive. There are no other viable candidates to take on any Republican candidate, much less Trump.

Personally, my favorite moment in 2020 was the Biden-Trump debate when Biden exclaimed (paraphrase), "come on, man, would you just shut up!" Perfect! Only Joe could have pulled off that necessary retort. An exclamation like that by a Williamson or Kennedy would not happen and if it did, it would sound flat and rehearsed.

The Democrats under Pelosi and Biden in 2021-2022 actually pulled off more than I expected in terms of progressive leaning legislation despite speed bumps like Manchin and Sinema. And you don't hear the Squad complaining. And it is not because they've been silenced, but because they know we are getting some progress, perhaps not as much as we like, but again, being a purist when it comes to legislation often means getting nothing.

The Democratic Party is the best place for progressives to make their mark.