Why are a lot of Americans so paranoid and such?

Ok, this is not a hate speech. But I've noticed that a lot of Americans on YA and sometimes Youtube are always paranoid about conspiracy theories and such. They seem to be either conspiracy theorists or religious fundamentalists. I know that not all Americans are like this- I've met a lot of very nice Americans. But why are a lot of Americans into the whole paranoia/conspiracy theory/ religious fundamentalist thing?