Thanks for the comment. To answer...

How does it make you better?

• By trying to put what you learned in your own words, you are forced to put the information you've learned into a coherent framework that other people can understand. By doing that, you will remember much better than by any other means.

Why blogging?

• Because in my niche, it is a way to Do and Teach simultaneously. By creating content, I'm increasing the numbers of followers that I have and therefore the future payout of my posts.

Am I not giving information to my competitor?

• I am. But one thing that I gain in return is trust which is much more valuable than information or knowledge. Information only cost time at this point with the internet and only a minority of people will actually implement "free" advice. From my experience, the information people act on the most is information that has a price tag on it.