None of them are really passive. E.G. an ebook is a lot of work and you need much time to write a good book, especially on a niche. And when you have it, how l

None of them are really passive. E.G. an ebook is a lot of work and you need much time to write a good book, especially on a niche. And when you have it, how long could it be sold, until the technical thing is outdated? A SaaS must be updated from time to time, bugs must be fixed .... A mobile web based game is much work too. A 100% passive income is really hard to find. Do something you like and try to sell parts of it (ebook, blog, saas, game, whatever).