Someone told them NO. You cant do that.

That made them feel mad and feel stupid.

Then someone told them that they were right and that someone else was actually the stupid one.

Then they felt better.

Better than better, they now have the secret knowledge and everyone else are the stupid ones.

There is no logic, only horse medicine.

Honestly, my suspicion is that you can easily get the stuff. I've gotten it for my dog once or twice (it's a lot cheaper than dog dewormer, despite basically being the same thing), and all you have to do is go into a Tractor supply or the like and it's right on the shelf, no restrictions or anything. This is in contrast to actual medicine, where I have to go to a CVS or the like to pay an overpriced amount for something that is more regulated, and might even be a bit of a placebo effect in the first place (look at flu meds for an example of that).

All of this mostly seems to speak more to the degrading of the American healthcare system due to costs ballooning beyond what some of the poorer in society can afford, so they are more willing to try folk remedies that may or may not work. And in the case of your grandmother, is she gonna risk paying a lot of her life savings to cure her tumors if they aren't benign (without a guarantee that it will work), or is she just gonna hope that the $10 treatment might make her feel better? If they're benign, then the $10 treatment "worked", and if they're not, then she'll get expensive treatment anyway, just probably be in a worse position to get it.

1. Ivermectin is a legitimate miracle antiparasitic
2. Early in the pandemic, some researchers showed you can neutralize COVID in vitro with ivermectin. The dose is more than enough to kill a human.
3. Trump announced he was taking hydroxychloroquine (antimalarial/antiparasitic) to prevent COVID infection during the pandemic
4. A group of crank doctors saw an angle and at a Senate hearing announced ivermectin as a wonder drug that prevents COVID infection entirely
5. Right-wing influencers like Joe Rogan took the ball and ran with it, infusing further anti-vaccine ideas into the movement
6. The sleeper class, who don't pay attention to medical news and get most of their understanding of the world from the influencers they follow, submersed in America's simmering broth of reactionary beliefs and distrust of authority, pick up the news that ivermectin prevents COVID during the Delta spike, when fears soared.
7. To a certain class of people, having their beliefs questioned is inherently hostile. Everyone telling them to not take ivermectin only makes them more stubborn about it. Ivermectin is also really easy to get a hold of because it's a common veterinary drug and pretty easy to find if you're rural.
8. Those people infect their social networks further with ivermectin bullshit, because people will trust their friends more than they trust authority.

And so, five years after we conclusively know ivermectin doesn't help with anything but parasites, you still find people who believe in its global efficacy, which has become greater and greater over time in reaction to more and more proof against it. Because the believers are stubborn reactionaries.

It's just one of the tenets of belief from the orange man conspiracy cult. They joined that cult and chose their special secret conspiracy "facts" to believe in.

Morons

Big Horse Pharma has their tendrils in more places than you would expect

It's honestly a pretty astounding medication that's been proven to prevent rna viruses from replicating in cells, and has some pretty cool anti-inflammatory properties. The main problem is that it isn't very water soluble and thus has horrible bioavailability. Basically, it would be as miraculous as people claim it to be if we can find a way to effectively deliver it to the treatment site.

Right now if you take it it primarily just runs through your digestive tract because it can't be absorbed into your blood stream. Which is why it's currently only useful as a dewormer medication.

My dog takes an ivermectin based heartworm preventative every month

My dog has never gotten covid or hantavirus

Need I say any more?

I mean it cures worms in horses, so it must be omnipotent

I did some limited research on this and there are a few studies that suggest ivermectin could disrupt tumors from forming. But certainly not enough evidence to suggest using it for that purpose given the risk of adverse effects.