People get seduced by a somewhat internal logic. They get a fuzzy feeling of superiority in their discovery that the mainstream ignores. If you point out the absolute lack of evidence of any of what they believe in, it's because pharma is silencing them. They are excited to be enlightened, because only they can see how crooked big pharma is: they need you to be sick so you can buy their "allopathic medicine" (derogatory calling of drugs that actually work), so they're trying to kill homeopathy who would really save you ; which to be fair is not helped by the fact that pharmaceutical companies are indeed crooked and want you to be sick.
I don't think there's any volume that can be said on homeopathy that will convince anyone who already believes in it that it's all a scam.