The Expert Beginner
A few months ago I read great article written by Erik Dietrich - How Developers Stop Learning: Rise of the Expert Beginner. After publishing this article, and receiving a lot of positive feedback, Erik has written multiple follow up articles. He also has written a book, which I decided to buy and read: The Expert Beginner ($5 for Kindle Edition!).
This book is a very interesting case study, in which Erik analyzes developer's growth, and how some people get comfortable with their current knowledge, stop learning, and are not willing to step out of their comfort zone. Erik calls this stage: "Expert Beginner". This leads to stagnation, and no interest to improve. What's worse it affects their coworkers.
I really recommend you to read The Expert Beginner. It's quick read (68 pages), and may help you not fall into this trap.