I hope your experience is different, but in my circle of experience, there are still people who well and truly believe that something incredibly conspiratorial occurred on September 11, 2001 — that the impact of two aircrafts could not have caused the collapse of the World Trade Center towers.
It doesn’t matter how often the conspiracy theories are debunked, people still believe it.
This may frustrate those of us with a more rational approach to the situation, but it certainly should not surprise us.
I’m not sure what the overlap between the two groups would be, but it helps to remember that approximately thirty percent of Americans (as of 2011) believe that the fortification walls of the ancient city of Jericho were felled by an army who did little more than walk around it several times over the course of a few days, culminating in loud shouts and trumpet playing (Joshua 6).