I've been a .gov employee at some level my entire adult life. And I find it hard to believe that there is a conspiracy to this level and breadth. I have never known any competence at secrecy, especially with so many people as would need to be involved here. We're talking about hundreds of people, if not thousands, who would have some level of inside knowledge, yet none of this knowledge has leaked.
That said, I'll also admit that I keep reading about theories because, like someone said, my needle is shaking.