First, nice article. Interesting takes. Question 1: Why didn't you just stay on Substack and change the focus of your newsletter to your eventual niche. It is fairly free to start, useful for newbees who don't want to shell out for an ESP.
Question 2: You talk about starting a course, but what about writers who don't write about making money, write about Medium or don't write about "Writing "?

Anyway, thanks for your article, great food for thought 😀 50 claps from me)