When your book project fails

I just spent two years working on a nonfiction book.
It failed.
The manuscript is going in a box, and then into storage. 

The project failed for five reasons.
1. I was not the right guy to write the book.
2. I did not test the idea to see if it was 'big' enough or compelling enough to support a book. Instead, I rushed into the project and wrote the book without a contract. The traditional method of writing query, then a proposal, and signing with a publisher is one a way to test the idea by exposing it to professionals like editors and agents.
3. I did not choose the correct nonfiction genre. There are several distinct genres for nonfiction. A few of them: narrative nonfiction, investigative journalism, collaborative (one or more co-authors), survey, general informational, self help/how-to, biography, inspirational and self-published manifesto. Each genre has distinct requirements for research, structure, and language. The genre you choose at the beginning of the project shapes everything that follows.
4.  I did not build an appropriate platform for the book as I researched and wrote it. As one agent said, "No platform, no project."
5. I did not stay abreast of the publishing industry trends. One way to do this is to regularly read the website PublishersMarketplace.com ($20 a month).

Sigh.