OK want to be a cool nerd who’s written a book on something like top ten conspiracy theories? It’s not as hard as it sounds:
1. Forget the notion that you need to do deep original research.
2. Buy the top ten books for your chosen subject.
3. Post a job to a freelance forum/mechanical turk with the job of someone else turning the books into a set of notes, combining common themes easily.
4. Read through the notes and turn them into text, so avoiding the charge of plagiarism. I did it all the time when a student at Cambridge University.
5. The originality simply comes from how you write the text, re-assemble the facts, and point out connections. You have to do this anyway to create a book from scratch.
6. Complete the writing, send to editor. Publish. Done.