Why doesn't Wining Boy play the piano anymore?

When Boy Willie asks Wining Boy to play the piano, Wining Boy says he's given the piano up. He tells a long story about how he started to feel like he was carrying his talent around with him like a heavy weight, almost as though he was carrying the piano itself. He talks about how he felt it was the only thing defining him, and how he realized he had to be something other than just "the piano player."