As far as examples of successfully kept secrets, I can’t give those, because I’m in on it.
All a conspiracy is, is a group of people keeping a secret.
As far as conspiracies not being successful long term, history tells us no such thing. Conspiracies with tons of people are successfully kept every single day, only to be discovered decades later when something is declassified for example.
You can never prove if a conspiracy to keep a secret is not successful if you never knew it existed.
Am I making any sense?
I’ve seen estimates as high as 10% of the population of east Germany were spying on their neighbors.
Naming conspiracies that have never leaked is kind of hard, since we wouldn't know about them. So you have to look for examples of things that were talked about after they stopped being relevant, or that were uncovered without anyone blabbing.
You sound paranoid.
