Ebooks are one of my favorite sources of passive income. Now, you can do this the simple way and just publish it on Amazon's KDP. Or, you can go all out and build yourself a book funnel. Book funnels are powerful, but they won't be fully passive. For example, if you do a free-plus-shipping offer for your ebook (converting it into a physical book), you'll need to create some one-time offers (i.e. extra training) and up-sells (i.e. an audiobook). But, a book funnel can be very powerful.
Again, no leader worth her salt will be attracted to such an opportunity. And anyone you do hire to lead the value creation, if they have two brain cells, will see that she's the one adding all the value. Sooner or later she will simply find a way to cut you out of the value chain, either by requiring more and more compensation, or by going off and competing against you (and actively at that.) Why does she need you? You're not adding any value anyway!
Creating passive income is the key to retiring, especially retiring early. If you want to retire early with the stock market you will have to save a huge amount of money, because that money has to last so long and retirement calculators depend on you using your investment to fund your life. With passive income you will have income coming in as long as you own the investment, without every eating away at the principle invested. Creating passive income may take more work than investing in the stock market, but I think it is well worth the extra effort!