An increasing number of people are taking advantage of having a leg up on their competition by branding themselves as "the expert" in their particular niche. Call it a business card, a resume, a billboard, or whatever you choose, but the long and short of it is that books are no longer just books. They are branding devices and credibility builders, not to mention door openers. Books are the reason that authors command large speaking and consulting fees.
Kytka Hilmar-Jezek, Book Power: A Platform for Writing, Branding, Positioning & Publishing
authors, book-power, branding, credibility, speaker, write-a-book