Authors are in the same boat as any craftsman. Once the original purchase has been made, the craftsperson gets what they negoitated for.
My husband is a carpenter, who makes cabinets and fine furniture. He's been reading this thread over my shoulder...and his opinion is "Once I sell the craft that I have poured all my talent, time, and skill...it belongs to that person. If they decide to sell it or give it away later, it would be great to get paid a 2nd time, but then, did the person ever own it? Or was it a short term lease, and they should bring it back to me when they are done with it?"
btw....he's also an avid reader, and looking at 4 rooms full of books, mostly paperbacks....he & I both think BC is great...share the wealth, opportunity..and if your lucky....travel with a loved one...as any books released by us would be