Nah, he turned deeply unpopular right after the debate with trump. He was hemorrhaging in the polls. His backers abandoned him because they feared trump winning. Several polls about biden dropping out had something like 75% of democrats wanting him to drop.

Kamala has ran to the left of biden on a number of issues. If this were a “billionares fear taxes” situation she wouldn’t have been the replacement. There are some rumors that establishment dems didn’t want Kamala to be the pick because of her policies.