Edward Current, the hysterical atheist who usually pretends to be a Christian Fundamentalist did a series of videos close to the 10th Anniversary of 9/11. In one, he admits to have been a 9/11 Truther himself until all evidence and logical inferences led him away from the nonsensical belief.
Now this video is pretty short, and very funny. He photo shopped some special effects and stated that it was a new video from a new angle:
Again, there is a special list of nut jobs out there:
Flat Earthers
9/11 Truthers
Moon Landing Doubters
Holocaust Deniers
Young Earthers
There are of course the willfully ignorant evolution and climate change deniers too.
There are probably very special people on this planet who fall into each of those seven categories. Are they among us (not in an insane asylum)? I would say, yes.