ETA: Okay, I’ve recently found out that this quote is not Vonnegut, although he did write something similar to this in a letter to schoolchildren. That letter was posted to three–ring’s blog with her commentary posted below. Her commentary was copy-pasted to Facebook as being written by Vonnegut, and it’s been passed around that way ever since. Proof here.
I’m fixing this post with proper attribution. I did do a quick web search before posting this, but apparently it was too quick. Bleagh.

I was playing racquetball with a group of colleagues. I finished playing and was sitting outside the courts cooling down when one of the managers came out of his game. I asked if he was happy and he said he was because he won. I asked if he had to win to be happy and he said, “yes.” I feel sorry for him.