[ghaff]

I'm not sure I'd ever recommend an ebook as a good passive income method. There are good reasons to write a book, including establishing credibility that leads to more revenue for consulting etc. But you're probably not going to make a lot of money from it.

[Jefro118]

I was referring more to relative passivity rather than income potential, but I haven't written one myself and I'm not too sure whether it's worth pursuing at all if your goal is money so I'll take your word for it.