From "When I'm Sixty-Four, Paul McCartney then and now " (The New Yorker, June 4, page 56) by John Colapinto
...The song contains a verse about his Beatles days.... I mentioned that the song seems to express amazement at the life he has led.

"That's exactly it, and I am amazed," [McCartney] said. "How could I not be? Unless I just totally blocked it off. There were four people int he Beatles, and I was one of them. There were two people in the Lennon-McCartney songwriting team, and I was one of them. I mean, right there, that's enough for anyone's life. And there was one guy who wrote 'Yesterday,' and I was him. One guy who wrote 'Let it Be,' 'Fool on the Hill,' 'Lady Madonna' -- and I was him, too. All of those things would be enough for anyone's life. So to be involved in all of them is pretty surprising. And you have to pinch yourself. That's what that song is about."

Damn! He makes a point. So, I've stopped hating on Paul McCartney now.