Propaganda doesn't work because people actually believe it. It works because everyone thinks that everyone else has that information, and that's what the authority wants to believe, so you keep quiet and pretend you believe it. So does everyone else. So in the end everyone complies.
But Solzhenitsyn said it better: “We know that they are lying, they know that they are lying, they even know that we know they are lying, we also know that they know we know they are lying too, they of course know that we certainly know they know we know they are lying too as well, but they are still lying. In our country, the lie has become not just moral category, but the pillar industry of this country.”
It's like these politically correct discussions, everyone knows what the elephant in the room is, but everyone pretends to not see it.