My friends who are Bernie supporters and who will not vote for Biden donʻt say anything about what you mention (idenitity politics, etc). Rather they blame the establishment, the Democratic Party who are as corrupt as the current administration. They say the Dems will not make movement on progressive policies. They wonʻt engage in conversation about what is it about Biden that is worse than Trump. Theyre just angry at the establishment, which they also blame for Trump winning in 2016.