As a course developer and promoter, I can say that on the face of of it, promoting can be easier than developing one. The upside of development though, is that once it’s done, have to do is keep it updated and it can earn you money for years. That’s the case with my SEO copywriter training course, which I’ve been teaching (and earning from) since 2009.
When you have your own product or service you hold a lot more control of the funnel from beginning to end. But I’ve worked with many marketers to help them better control the best affiliate marketing funnel with banner ads, blog posts and social media. Once people move from those elements to the sales page – I help them control their message and email marketing campaigns and everything behind the scenes.