I actually think it also comes from a lack of understanding. Many people don't know what DnD actually is, they just take that information on spoofs and comedies of the game they see on TV or the internet. Or some are just really conservative with religious backgrounds such as my mother. The first time I told her that I played Pathfinder, she said, "What?! That is some demonic stuff Josh, people have died playing that game"! Of course she was referring to those few incidents in the 90's were some guys from Europe took the game a bit to far, but I basically just had to explain to her that there was nothing wrong with, it was just a game of pretend with rules, and dice. Luckily I was 20 at the time and there was not a damn thing she could do about it, it's not like I was holding the events at her house.