It isn't about him. It's about the future of US democracy.
He is responsible for destroying his chances following his disastrous debate performance.
It's only because he blew it so monumentally that folks are looking for someone who can beat Trump, and not him.
Biden was the best candidate last time around. This time, he isn't. A younger, livelier candidate is. If he admitted that it's about the future of the country as a democracy, and that people see him as a big risk to it, he'd know he must step aside. But it sounds like he doesn't get it yet. He's blaming everyone else.