Flatearthers are harmless. I’m not even completely convinced they are not just collectively trolling us. Anti-vaxxers mean while are responsible for weakening herd immunity in western civilization and by doing so, the killing of hundreds of people who got sick and died because of it.
The measles were basically extinct, now they are even killing people in countries with low amounts of anti-vaxxers. And why? Because a group of stupid people got together on Facebook and decided they wanted to create a version of reality where vaccines were evil.
Vaccines have side effects. Not taking them, however, has much worse effects. Worst case means you’re quite literally murdering people who can’t survive neither the vaccines nor the disease, best case is things like the HPV were it’s just you or your children getting completely avoidable cancer (still extremely tragic).
Hell, even Donald Trump has done far less lasting harm than anti-vaxxers.