If you do something for fun and don’t get paid for it, you’re called an amateur. If you do the same thing and do get paid for it, you’re called a professional.
That would make me a professional writer, as I have been paid for things I wrote many times. I also foolishly gave away things I wrote for free when I sent letters to Dennis Rogers at the News and Observer that he used in his column. I do not regret those letters he printed as it got me writing exposure, and he turned out to be a very helpful friend.
However, I do wonder sometimes at how people who know you are a professional while they retain amateur status will go up against you anyway. Are they crazy, or just underestimating my abilities? Could be a little of both.