I'd posit a fourth group: people who make a fortune selling snake-oil alternative "treatments" in the lucrative Alternative Medicine industry.

I don't get mad at parents who don't vaccinate. They're trying to do what's best for their children, and I simply try to educate them better and hope that they're willing to listen. I do get mad, however, at the people lying to these parents for the sake of profit. They belong, in my opinion, in jail.