“Writing is like sex. First you do it for love, then you do it for your friends, and then you do it for money.” Virginia Wolf phrased that quote. Sounds great and always wins applause, but I don't believe it is true. A professional writer always tries to write something meaningful that is important for himself ("for love") and, at least in his opinion, for others, too ("for friends"). And if he succeeds he will probably make some money. There's not necessarily any moral descent or self-betrayal involved.