If everybody in your community is vaccinated against a severe infectious disease and you refuse, you're still protected because it is extremely unlikely you'll be exposed to the disease in a community with strong immunity.
Once vaccination becomes a lifestyle choice and people start opting out as a symbol of freedom and self determination, that passive protection is lost and you run the risk of epidemic- not just among the unvaccinated, but possibly also affecting those in whom vaccination didn't work so well.
IOW some people are harshly critical of conformity in others even though their alternative choices rely on it.
This isn't new- Europeans have only been able to pursue their vision of peace and prosperity because of the US military, but lets not go there ;-)
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1
