"This campaign is bigger than me or you. Everything we believe in, everything we stand for, and everyone we are fighting for are at risk in this election." --Joe Biden campaign email, July 4th
"if I lose it's cool lol" --Joe Biden on ABC News, July 5th, paraphrased
This is an argument for why Biden is able to lead. Speaking for myself, I'm not so worried that Biden is unable to lead. He's old and obviously slowing down, but he's got decades of experience and, as you say, a whole administration's worth of expertise.
I'm worried that he is unable to win.