When my agent told me that they were pursuing translation rights for Quiet, Please, I figure maybe Germany might buy it, or France, or perhaps Spain. Then I got the news that the first offer had come in. It wasn't from any of these countries; it was from Taiwan, who wanted to translate it into complex Chinese. The publishing business is funny that way...subjective; you can believe with 100% certainty that someone will be interested in your book, but ultimately it usually goes to the person you least expect.
In the ten years I've been writing professionally, I have had what I thought were great ideas for books; none of these ideas ever panned out. I never imagined the first book I would published would be a memoir. I figured one day if I had a mildly successful publishing career I would write about my life, but here I am, 29, and already have a memoir under my belt.
So to those who want to right: DON'T! It will only leave you drained and sad. But to those who are writing, keep beating on, keep submitting those ideas, and keep having hope...it's a subjective business and one day, when you least expect it, your day will come.