But I don't necessarily blame said people, at least in the proximal sense. The technological industrial complex continuously refines its understanding of the desire for novelty that's always been there and seeks to exploit it; and they've gotten unreasonably good at that. It doesn't matter if your intellectual property is just as relevant as ever, perhaps more so, if there's some hip new alternative. Udemy and of course social media sites know this, and I think there's a feedback loop that goes beyond mere exploitation of the human psyche, but in the actual training of the human psyche to have blindness towards the past.
The only answer right now, besides hosting your own courses (with hookers and blackjack), might be to periodically recreate your online presence from scratch in order to exploit the algorithm back. If your courses on Udemy aren't seeing the traffic they deserve, close your account, and create a new one... assuming that's feasible and they don't check too hard. With the current state of AI, this may just be a cat and mouse game that can't be sustained.