The main problems I see are that for Biden to win, he needs not just the core "Blue No Matter Who" vote, but a broader coalition. In 2020, that included young people, and politically unaware people who were upset about COVID. In 2024, he's doing everything possible to alienate the youth (via support for genocide, and violence against protesters), and the politically unaware people are upset about the economy. Trump isn't any more popular than he was in 2020, this is entirely an own goal on the Biden campaign's part.