"Writing is like sex; you start out doing it for love, then for a few
friends, and you wind up doing it for money."

In searching the web, I have found at least three sources for this
quotation (or slight variation): I had always thought it was Dorothy
Parker, but didn't find it books of her quotations. Various web site
credited Moliere, Oscar Wilde, and Virginia Woolf, and anonymous.
Which, if any, is right? Please include citation in your answer (e.g.
book title or such).