Are you forgetting which site you're on? This is HN, which is a hotbed of anti-vax, QAnon, and various other crazy conspiracy theories. This shouldn't be a surprise: it's an American site, and most of the readers are American, and half the American population has become big believers of that stuff lately, so of course a sizeable fraction of the readers here are strong believers in such things.
https://www.politico.com/news/2023/09/24/anti-vaxxers-politi...