I am not a doctor but on several occasions I have known more about something than a doctor did. I find it very amusing that some purported doctor will make claims that are contrary to any number of actual studies, and the real-world results -- and someone who is suckered by them thinks that we should all believe and respect the "genius" of some doofus?
Ivermectin has very little evidence of efficacy. Taking it in veterinary medicine form, like horse paste, is so incredibly ludicrous that, well, I can't even.