Well, money was my reason.
Here's what happened: Back when I started writing seriously I read a lot of books about how you should pitch your book to an agent. Most of these books included sections on both fiction and non-fiction. Even though I'm a MG fiction writer I was interested in reading how the other half pitched as well. And, as I read those sections on non-fiction book proposals, the seeds of an idea started taking hold in my head.
The one thing I read over and over again was (as the Postkeepers detail) the need for a pre-existing platform, or your current way of reaching your audience of potential, future book-buyers.
For 16+ years my wife and I had been doing Arts and Craft Shows, spending many a weekend driving to shows, setting ups, dealing with displays, customers, the weather, credit card machines, wonderfully pleasant/horribly obnoxious neighbors, then breaking down and driving home again. I had noticed there were no books on getting into the Arts and Craft Show business and with all of my experience, I figured I could be the person to write just such a book to fill that need.
I sat down during a lull in a three-day weekend show and started writing a list of potential topics to write about. If I could come up with 100 topics, I figured I had something. I would start writing a blog about doing Arts and Craft Shows to (a) develop my platform and (b) serve as first drafts for the content of the book.
I came up with 120 without working too hard. So I bought a catchy domain name ("The Art of the Craft Show"), installed WordPress, and started writing blog entries.
At the time, however, I was completely burned out on doing craft shows. I was tired of the weekends spent making jewelry, the weekends spent doing shows, the constant worry about the weather, the national economy, the local economy, the dwindling sales, and a host of other factors that were completely out of our control.
In short, I hated craft shows.
I suppose I was the only one who was surprised to find that I also hated writing about craft shows.
Or, that after four months of trying to write even short sections of a book that I had a good chance of actually selling, I gave up on it. Writing those blog entries became worse than work, worse than even doing craft shows. They required an enthusiasm and energy that I could not fake. Despite getting a few regular commenters, within weeks I found I was starting to resent the whole project and actively dreaded the day of the week I had chosen to write/post new articles.
Eventually, any time I sat down to try and write the black cloud that had become The Art of the Craft Show settled over me, all-but dooming my MG fiction work. Didn't I have an TAotCS blog entry that needed to be written? Why not try to crank out a couple of them so I'd have a weekly posting backlog to carry me through a month or two? (Even trying that didn't work.)
As much work as your writing takes, it deserves your full attention, your love and your devotion. Doing otherwise won't fool anyone, especially yourself and your writing.