It was an Inside Job
By far the most widespread tale espoused by 9/11 conspiracy theorists - often referred to as “truthers” - is that the United States government either helped the attackers succeed, or orchestrated the entire thing themselves.
“Experts say part of the reason for the persistence of such conspiracy theories is the dissonance that results when people hear that a relatively small group of men using low-tech weapons caused such cataclysmic carnage,” says the BBC.
Project MKUltra was the code name for a series of investigations into mind-bending substances, techniques, and medical procedures. The goal was to develop truth serums, mind-control drugs, and determine what chemicals and methods had potential use for torture, disorientation, and espionage.
The experiments started in 1953 and were slowly reduced in scope over the next 20 years before being halted in 1973. A variety of experiments were undertaken to understand the effects of powerful drugs on unsuspecting subjects.
FDA is Withholding the Cure for Cancer
You've probably heard this conspiracy theory before, maybe from your uncle who still has his doubts about the Apollo 11 moon landing, or on a Reddit thread exposing the evils of "Big Pharma."
It goes like this: A cure for cancer exists, but pharmaceutical companies — and perhaps even government health agencies and cancer charities — are suppressing it because they make so much money from treating the disease or fundraising for it.
Lincoln and Kennedy Coincidences
Not long after the assassination of President John F. Kennedy in 1963, the a list of seemingly amazing coincidences between the two men’s lives appeared, and it has been widely and continuously reprinted and circulated ever since:
Abraham Lincoln was elected to Congress in 1846. John F. Kennedy was elected to Congress in 1946. Abraham Lincoln was elected President in 1860. John F. Kennedy was elected President in 1960.