re: Are conspiracy theorists the most dangerously stupid segment of the population?

Yes they are. And they span all the way across the spectrum, left to right. It used to be almost exclusively the Right in the 1950s- 1970's until The National Review took down the Birch Society and then it shifted back to the Left. Now it's both, idiocy from all sides.

There was a famous essay decades ago called " the paranoid style of American politics" . You should read it.