The Argument from History
Conspiracy theory arguments generally fit into about four arch-types. There's the contrary evidence that is used against the official position, the random evidence which doesn't contradict the official position but is stuff left out because it is irrelevant, the argument from special pleading where "facts" are just made up and if true would support the conspiracy, and there's the argument from historical example. Conspiracy theories have an uphill battle challenging the accepted view on a purely rational basis. We may not trust everything that the government says, indeed we should not, but the official story is usually evaluated by experts. People that have spent their lives in a specific field that do not have merely their jobs on the line but their life's work. An Egyptologist isn't making a mistake in ignoring the "aliens did it" hypothesis, they've figured out the method by which the pyramids could have been built and then wrote a public