There are numerous reasons why you should consider writing a book:

1. You are passionate about a tool or technology. You want the world to know all about it.

2. You know there's a book in you. You've had a desire to do something creative, something different for some time. Many authors find a book project to be an exceptionally rewarding and fulfilling process.

3. Increase your credibility. By writing a book, you become a "name" in a given area. Of course, you might already be well known, but a book can only reinforce things. Become a superstar.

4. Increase your visibility. With a book behind you, it is far easier to reach a global audience. Become the world famous Go-To Expert.

5. Gain a competitive edge. With increased credibility and visibility you can leverage your existing career. Many of our authors report that they have secured new clients on the back of their books, or that work promotions have been fast tracked. If you are an independent consultant, you might consider charging a little more.

6. Earn money. If a book sells well, income can be highly lucrative.

7. Writing enables you to broaden your horizons. A book can potentially allow you to move into areas such as training, consulting, and presenting.

8. Use a book project as a way to learn new skills, or expand the ones you already hold.

9. Leave a legacy, and make your Mother proud ;)
Source: authors.packtpub.com