University professors, politicos, players in professional services, and business leaders understand the game. A well-done book, with respectable sales, establishes its own kind of credibility. Not having that is conspicuous by its absence. Analogy: Trying to conduct business in 2014 without a smartphone.
However, the respectable sales part has become harder. In Tech Crunch, John Biggs points out that probably 1 new book is listed on Amazon.com every 5 minutes. That include the rapid growth among indie or self-published books. The advantage of self-publishing to authors is that there are no gatekeepers. Anyone can put a book out there. Here is the Tech Crunch analysis.
That's part of the problem: A glut. The other part is that dismal sales are highlighted through the Amazon system of sales tracking. You bet, you look bad if your book never got off the ground.
For those 2 reasons, authors who intend to leverage the book for a marketing purpose, be it getting elected or developing new business, have to factor in the cost of publicity. That's a must-do. No, it isn't cheap.
When putting together proposals for ghostwriting projects, I now include a section on publicity, ranging from tactics to possible vendors. The price can range from a mere $75 an hour to $15,000 for a month's effort. Those publicists who charge an average of $285 an hour usually won't take less than a $5,000 assignment.
Publishing a book without beginning a quality publicity campaign before it's out in print seems downright reckless.