Except I wasn’t wrong. If he had stayed in I believe he would beat Trump. He only dropped out because he could see the party infighting, and dropped out to try and unify the party. But, had he remained in the race, he ultimately would have beaten Trump. The only way we would know if I had been wrong was if he had stayed in the race and then lost, otherwise I still believe in the end he would gave defeated Trump.
Polls 5-6 months out of the election are not indicative of how people are actually feeling. In the end, when the election actually happened, I believe people may not have been excited to vote for Biden, but I believe people would have definitely not wanted Trump to win. As I said, Biden already defeated him once in part because of that reason.