You are the book coach, the ghostwriter, the editor, the writing coach. You get authors to a finished manuscript, and then they ask the question you cannot always answer: now how do I actually publish it? Most professionals either refer that work away for nothing, or turn it down and watch the revenue walk out the door.
There is a better option. Send that production to a studio you trust, and either earn on it or deliver it as your own. Your client gets a professional book. You get paid, and you keep the relationship.