[JoeMayoBot]

Both my experience and most other authors I've talked to don't make a lot of money from book sales/royalties. In one case that I know of, one author self-published a book on a niche subject that no-one else was writing about and made a fair amount of money (over $100/book). Other author's I've spoken to have made more money self-publishing than through a publisher. One of reasons why some authors write is because they're independent consultants or part of a software house where the book is good for marketing. It's a nice calling card that might be attractive to a certain type of customer (especially via a well-known publisher). There are other intangibles like personal growth and teaching others that might contribute to your later success. Teaching others can be a forcing function that makes you think about a subject more deeply. So, while you might not experience immediate financial gain, there are often future gains from the endeavor of writing a book.