If someone says to me “See, there’s these twenty thousand people in this conspiracy, right,” I throw up a red light. This person doesn’t understand what a conspiracy is, or how it works. Twenty thousand people could no more be in a conspiracy than they could be in a boy band. Conspiracies exist by LIMITING the number of people who know. Because every single person who knows is another person who could blow it.
You notice something about these major conspiracy theories? No one with any credibility whatsoever has ever stepped forward and said “Yes. I was a part of this.”
That’s a good way to tell if a conspiracy is plausible, btw. Numbers. Too high and it’s impossible. And I’ll tell you why. A conspiracy can’t involve too many people at all. Not who know exactly what’s going on. You might find some compartmentalization, where some of the actors know SOME of what’s going on. But any conspiracy with more than twenty or so people–and that’s about the largest I can imagine–is running serious risks of exposure.
People talk. People trust people they shouldn’t. People get intoxicated. People feel guilt, and peer pressure. People have emotional issues. People change their minds. The more people involved, the higher the chance this will happen to one or more of them, since disaffection can spread like a virus.