Paul McCartney in a 1984 Playboy interview:
PLAYBOY: Whatever else you say, people have always felt you are
commercially minded, that you are motivated by money–PAUL: No, it isn’t money. It’s doing well. I saw that Meryl Streep said,
“I just want to do my job well.” And really, that’s all I’m ever trying
to do. I still like writing songs. It still gives me a thrill. If I had
been asked at 15 why I wrote, I would have answered, “Money.” But after a
while, you realize that’s not really your driving motive. When you get
the money, you still need to keep going; you don’t stop. There has to be
something else. I think it’s the freedom to do what you want and to live
your dreams.