This is a fundamental misconception.
One of the world's great liars told us how it's done:
"All this was inspired by the principle—which is quite true within itself—that in the big lie there is always a certain force of credibility; because the broad masses of a nation are always more easily corrupted in the deeper strata of their emotional nature than consciously or voluntarily; and thus in the primitive simplicity of their minds they more readily fall victims to the big lie than the small lie, since they themselves often tell small lies in little matters but would be ashamed to resort to large-scale falsehoods.
It would never come into their heads to fabricate colossal untruths, and they would not believe that others could have the impudence to distort the truth so infamously. Even though the facts which prove this to be so may be brought clearly to their minds, they will still doubt and waver and will continue to think that there may be some other explanation. For the grossly impudent lie always leaves traces behind it, even after it has been nailed down, a fact which is known to all expert liars in this world and to all who conspire together in the art of lying."
— Adolf Hitler, Mein Kampf, vol. I, ch. X
The bigger the lie, the easier it is to get away with, because people simply refuse to look at the evidence it's a lie.
Look for example at vaccines where the evidence could hardly be clearer. It's all published in the scientific literature for anybody to read, and it's not controversial there. There are subjects like autism and aluminum where the evidence is absolutely one-sided and the pro vaccine side have absolutely no emprical scientific papers to cite. But they just claim they have them, never actually citing them, and 98% of the population believes them. There are numerous credentialed and/or insider whistleblowers, but the media whitewashes or ignores them. https://truthsift.com/graph/Does-the-preponderance-of-the-evidence-indicate-vaccine-aluminum-causes-autism/732/1/-1/-1/0/0/0/0/0/0/0/0/0/0/0/0/0/0/0/0 And this is a case where people have personal experience: more than half the young children today have chronic illnesses even according to CDC. And it's also a case, where this published scientific evidence Is absolutely determinative. It defines the evidence and it's all one-sided, but in spite of all that, the lie still prevails because almost everybody doesn't look at the evidence, exactly as Hitler said.
It's also worth noting that whistleblowers are unimportant. There were numerous 9/11 whistleblowers. Media doesn't cover them and nobody cares. And claims that projects are too big for the governmen to cover-up, are also clearly false. They just compartmentalized knowledge, on a need to know basis. Los Alamos had hundreds of thousands of employees, but almost none of them knew what was going on. Bletchley Park had 9000 employees, but again almost none of them knew what was going on.
The government can get away with anything, and routinely does, which is one of reasons why so much is fake.