Writing a book that makes millions, unless you’re J.K. Rowling, is very unlikely. There isn’t, frankly, a lot of money in books.
However, writing a book that sells precisely to the people you’re trying to market to can make you millions.
When you narrow down your target market to, say, the few dozen or few hundred people that will, in turn, use your expertise for private consulting or high ticket speaking engagements, your book doesn’t need to sell millions of copies to make millions of dollars.
Smart authors rely on “backend” sales, or selling high-ticket items like private coaching, consulting, speaking, or contracts in their service business.