The Book all User Experience professionals must read: " Gurus on marketing" by Sultan Kermally. You will not find a book that will summarize Peter Drucker, Theodore Levitt, Micheal Porter,Philip Kotler, Tom Peters, George Day, Jagdish Sheth, and Thomas.T Nagle so brilliantly.
If you are asking why should a User Experience professionals read these books, then my friend, you are in serious trouble.
We ( UX, OLM, Analytics, Product folks, Designers) own perhaps the most valuable real estae which is perhaps the cheapest to buy. Think about the responsibility we have. Go on, think about it