There's a chasm between the epistemic question of "does this drug really work?" and the pragmatic question of "does a risk-reward analysis under uncertainty say that I should take this mostly safe drug that might slightly reduce my covid severity?"
FWIW, I wouldn't take ivermectin either as a prophylactic or therapeutic, the evidence just isn't strong enough, but I don't really fault anyone that would add it into the stack of treatments upon a diagnosis in the hopes of a small net benefit.
That's not a given, that depends on the patient, the dose and a host of other factors. You may well end up harming someone significantly. You are in no position to proscribe any kind of medication to someone else unless you happen to be a licensed practitioner.
"That's not a given"
"You are in no position"
It is true, but unfortunate, that in many societies only licensed practitioners are in a position to prescribe (or proscribe) most drugs. That's a policy that does some good but also an enormous amount of harm.
- Silicon valley rationalist types taking stacks of vitamins despite having no evidence on bioavailability because they are generally without side effects and who knows, you might live forever. I think the consensus on this now is that more or less this is not a useful practice, though I am unaware of any evidence for it being unsafe.
- Prophylactic hormone replacement therapy in middle aged women, which was eventually generally recognized as unsafe because of unexpected cancer risks not initially understood.
- Prophylactic breast self-examination, mammograms, and prostate exams based solely on age, the former of which have been significantly dialed back over the last decade because the risk of false positives or catching slow-growing low risk cancers causes a net negative from the treatment. I don't know what the state of prostate exam research is.
- Prophylactic aspirin for heart stuff: we seem to go back and forth on this, but the last I read was that actually there's mounting concern about chronic low-dose aspiring. At the very least, it's not obvious this is doing anything.
- Statin treatment in response to mild elevated blood pressure with no symptom of disease; not exactly prophylactic, but close in the sense that it's about advance management of expected disease. And last I read, researchers were increasingly recommending dialing back statin treatment for minorly elevated blood pressure because of, again, unforseen side effects.
So I just mention this to say that what I take from your post is "the precautionary principle suggests giving more weight to prophylaxis with no known side effects" and what I take from major medical stories in my lifetime is "no known side effects almost always turns out to involve side effects in the end, and that has to be part of the precautionary principle as well".
And I should note all of the above prophylaxis is based on clearly defined treatment regimens and physician supervision, not the kind of wild west ordering various formulations of ivermectin at unknown doses with or without medical supervision on an ad hoc basis.
I didn't say that I don't fault people for taking it as a prophylactic. I do fault people for doing that because the side effects of long term use are less known, as you say.
I had alarming symptoms after the chloroquine treatments, and regret having done it. But nobody would ever put chloroquine in the "no known side effects" bucket.
If you're familiar with software development, this is akin to "there's a bug in my codebase and I'm just going to add a bunch of code that probably won't affect anything in the hope that it will fix the bug".
Meds shouldn't be administered in this way. It just ads noise to the system and will complicate things down the road.
Also, I don't like your first sentence, it's a rhetorical gotcha that is actually not in line with the medical establishment's thinking on ivermectin's hypothesized mechanism of action:
https://www.covid19treatmentguidelines.nih.gov/therapies/ant...
If they were miracle drugs as described the effect would be so large that those studies would be unnecessary. But here we are, and study it we will.
There is tentative evidence of a small to medium effect, but the quality of that evidence is low and that quality is insufficient to recommend use. This then deserves more attention and resources to figure out if it's real and why there's an effect. That's how science works.
Contrary to your claims here, scientists aren't studying it because some cranks on the internet propped it up. They're studying it because some field doctors had positive anecdotal experiences and some early studies showed promise.
As you've said, the medical establishment really wants to end the pandemic. Which is why they're looking into this drug, among many others.