I assume you mean that you wish you could have written the book, since you had the same ideas on your own, but now that you’ve read the book, it would be plagiarism to write your own.

I also assume that you have just read such a book (The Pirates Dilemma would be my guess, based on your Twitter update). I don’t think I’ve ever read a book that I wished I had written first, but I have certainly read articles and blog posts that meet that criteria.