Don't forget the "liberal" (closed minded in their own way) hippie types who think cancer can be cured with some magic herb or something. They are just as likely to be against vaccines and science in general. I know too many of these people.

They are so insecure that they view any type of education as a direct insult to them or some stupid bullshit like that. Like deep down, they know how ignorant they are

They know deep down inside that they are dumb and uneducated but think their "instincts" and gut feelings are equivalent or better than years of studying and analytical thought. They also are jealous of people smarter than them and instead of raising themselves up they prefer to pull them down.