I run a company that sells courses. We've built our own audience, which is what makes this possible. We hire instructors with the goal of working with them in the long term. (Basically, for them, our goal is for it to be the perfect part-time job.) I would recommend looking for a publication in your niche that also runs courses, and approach them about the possibility of hiring you. You could also approach an established publication, and offer a partnership, in terms of establishing a course-based business. Don't look for a platform, look for a company that you can have an actual relationship with.

youtube is better.

Guess you did not read his comment very thoroughly. He answered your question.