Eventually public opinion gets so swayed that no amount of evidence could ever sway.
Hypothetically, if evidence was found proving that any major historical event was manufactured but people were already so strongly opinionated about it it would have no sway with the people.
For example: If evidence were to come forth that North Korea was a Utopia and the world had been lying to us, and it was legitimate *(which it by no means is, this is hypothetical) there would be no large amount of people who would accept the new ideas as legitimate.
Wouldn't it be easy to prove with transparency?
This hypothetical can be tested versus hypothetical about an all mighty being...