Anti-vaxxers are relentlessly criticized everywhere. They don’t have a protective social bubble. The criticism they receive from people they assume are brainwashed idiots only strengthens their beliefs.
the reason they're able to dismiss criticism is because there's a bubble of people and content (blogposts, videos) that are being fed to them via social media, gradually convincing them that they are right. if social media like Facebook showed a more "objective" collection of content in your feed, you would end up with <1% anti-vax, flat-earth, climatechange-denial etc. content, and it becomes much harder to hold on to this conviction.
