Anytime anyone with any brains can see that the official explanation doesn't add up (e.g. JFK assassination, 9-11) alternative theories will pop up. Unfortunately, most Americans are too scared and/or lazy to look for truth, and prefer to call those who question the official line of BS "conspiracy nuts".
Personally, I have no patience for the head-in-the-sand crowd, not just because I detest intellectual laziness and cowardice, but also because their attitude threatens my (and everone's) freedom.