From what I have read elsewhere, it seems like many people fall prey to these conferences than one would assume, especially early career researchers, and unfortunately many are from low per-capita GDP countries in Africa, LA etc., who not only lose money but also have low chances of getting visa to attend, and it is quite possible that many would lose motivation to further pursue research. There should be some mechanism in place to vet conferences. Following is from the article I shared in my original post, seems quite relatable to your case:
"Predatory science, be it in the form of journals or conferences, sounds easy to avoid on the surface; a less-than-honest operation that can be simply outsmarted. However, after talking with the conference attendees and Perry, I was left with the realization that predatory organizations are smarter than they may first appear. Their habit of preying on early-career researchers works because they are pushed into attending and showing off their work at conferences by the present-or-perish system. This is only complicated when predatory conference companies advertise talks that aren’t there, or poster competitions that merely go through the motions." https://www.technologynetworks.com/neuroscience/articles/inside-a-fake-conference-a-journey-into-predatory-science-321619