Most things claimed by conspiracy theorists are just cold hard science. It takes an act of conscious denial to claim they are not true.
Like the one conspiracy theory that most people are aware of - the JFK assassination. You are required to believe that a bullet can stop in mid-air, change trajectory, take off again, go through 2 bodies and end up without a scratcb on it.
The second good conspiracy theory requires you to believe that 2 planes can crash and desinegrate into it's molecular particles. Of course, that is the pentagon and pennsylvania 911 plane crashes.