I got as much for the option as I did for writing one of the books, and I discovered that being a book author caused people to respect me much more than if I was a mere screenwriter.
Since my Hollywood book came out, I’ve discovered that top-level people in Hollywood will read my material, with or without agent representation. And, since I have a proven track record in selling both books and scripts, I don’t lose my career if the Writers Guild chooses to strike. I’ll just write another book.
If I teach a class, do a lecture, or give a seminar, I tell writers to write whatever they are passionate about. To sell it, they only need to know the rules of the particular game they’ve chosen to play. When you know the rules, any game is easier to win.