I tried KDP for a short time, in 2023 and I saw that there is potential. Unfortunately amazon did a mistake and suspended my account - but after some emails, and 3 months passed, they reopened my account. But then, I lost ranking of my book from being top 3 in its main keywords to pages down. That book alone, was profiting me 500€/month (spending 500€ in ads or something like that)
I want to get back to it, but it's so hard to compete with people who buy reviews. Do you buy reviews? How?
Btw - there are different strategies of selling your ebook course. For example, you can create a twitter account in which you link to this thread and update also there. At the same time, you follow/unfollow whoever follows other guys who are selling KDP courses. Same can be done on instagram.
Also you can try to post your product on gumroad and write proper sales copy there with SEO + ads you might get profits.