Big pharma! Conspiracies, thankfully, are not very likely to be true. As I wrote for BBC News, math research shows that any given conspiracy is prone to fall apart because one of the conspirators eventually will blow its cover. People aren't very good at keeping secrets, and the more conspirators necessary to keep a conspiracy going, the more likely it is to unravel. The problem is compounded by outside forces, such as journalists, investigators, and regulators, who are always on the lookout for suspicious activity.
Imagine just how many thousands of people would be necessary for Big Pharma to suppress a cure for cancer, a shockingly common conspiracy theory. David Grimes from the University of Oxford estimates that at least 714,000 people at eight different pharmaceutical companies would be required to pull that off. And that figure doesn't include employees at smaller companies, academic scientists, the FDA, or health journalists.