Actually, they are encouraged by the powerful. If the masses are caught up in nonsense it keeps them from concentrating on what is really going on, like the wealthy stealing from the poor or the wars on middle eastern countries. So, the mainstream media encourages it to a certain extent. Plus there's a whole industry built around conspiracy theories, JFK; 911; all the right-wing conspiracy theories involving Obama. Publishers know they can make money with this stuff. You always have to be careful when trying to figure out who you can believe.