They're dangerous in that they make completely misguided and ignorant people believe in things that aren't really there. The very fact that some people actually answered yes shows the danger to intelligence that these things are a part of.
The supernatural, religion, crazy metaphysics, horoscopes, etc. They're all contributing to the dumbification (it will be a word) of humanity. Anyone who accepts something as the truth without there being any physical evidence at all is not in any way shape or form using intelligence. The only "evidence" out there supporting stuff like this is purely anecdotal and coincidental. No causation has ever been shown.
So physically dangerous? No. Danger to intelligence and therefore society as a whole, I guess.