I don't disagree with any of this.
My first point was that we don't know who was sampled. We need look no further than election polling to tell us that there may be selection bias which may skew results.
My second point was that there may be elements of more mundane conspiracies wrapped up in the truly bogus conspiracy theories or beliefs.
For example, there is simply no fucking way that 54% of Americans believe that 9/11 was an inside job, planned by our government, with controlled demolition, and a couple of misses to make it beleivable.
I would expect the actual % to be more in line with Bigfoot or faked moon landing numbers.
However, if the 9/11 "conspiracy" means that there was a probable cover up of the incompetence involved in monitoring the hijackers' activities, providing realistic threat assesments, and learning from the attempted bombing in 1993, then I think that is where some of the high % comes from. That and, again, the people who were polled.
Also, with some of the more supernatural stuff, the results are not a stretch. Our own president is a practicing catholic who beleives that Jesus was raised from the dead, transsubtantiation, and biblical prophecy.