More common than you think unfortunately. The internet has given anyone the option to find their mental echo chamber.

My parents are hispanic immigrants (both citizens) who voted for trump, are republicans and also hate immigrants. They believe all the Obama drinks children blood stuff, are antivaxers, and since my older sister is with them, she is now also an antivaxer so her children have zero shots of any kind. (Good luck to them in the future if they want to travel)

One of them believes aliens speak to them. I’ve seen a group in my family go to cult like events where they all dress in the same white uniforms and talk about the universe.