Fully agree. I know a completely non-famous #1 bestselling author for courses on how to develop iOS apps. 99% of the revenue is coming from the books and course

Fully agree. I know a completely non-famous #1 bestselling author for courses on how to develop iOS apps. 99% of the revenue is coming from the books and courses. 1% of the revenue is cheap app re-skins + good marketing. In the early days, they actually used course revenue to subsidize their app operation to keep it afloat. So yes, they teach you how to build iOS apps. But those apps have a negative ROI.