The old saying holds: If you want to make big money, get a job on Wall Street. It's rare that a book author will become wealthy, at least not through the royalties from books. Hugh Howey, as Joshua Brustein points out in Bloomberg Business Week, is the exception. Here is that analysis.
Also, increasingly it's irrelevant whether the books are produced by a publisher such as HarperCollins or a self-publisher like iUniverse.com.
Sensible authors engage in this task primarily as a labor of love or as a marketing tool.
The labor of love takes the form of a willingness to invest oneself in getting a story out. It could be a memoir of growing up rich in Europe and will be self-published. The family loses all the money. The family comes to America and doesn't regain the money. Instead it establishes a center to help other immigrants learn the language, find survival jobs and start to build a better life for their children. The author will distribute the book to about 500, feel tremendous satisfaction and that will be that. Along the way, of course, could be invitations for lucrative speaking engagements and one from a standard publishing house to do a book which will earn money.
More often, at least in the kinds of books I ghostwrite, is the short book to be distributed as a device for branding and promoting a certain theory or point of view. The ultimate goal is developing new business. For those in professional services, this is a must. Sure, there is a price listed on the book. After all this is capitalism. What doesn't have a price doesn't have value. But most often the book will be distributed for free as part of attracting prospects as well as media attention.
One of my books for my own byline is through an established publisher. The other two are self-published. I didn't get rich. What I did get was more assignments and invitations to speak. That's all I expected. So, there was no heartbreak.