Which is the silliest? Which has the best possibility of being true?
Not a direct answer but perhaps interesting.
I saw The Parallax View with Warren Beatty when it came out in 1974. "The story concerns a reporter's investigation into a secretive organization, the Parallax Corporation, whose primary focus is political assassination."
I'm not much for conspiracy theories in general, but this movie had me sitting in the theater thinking
well after the credits had rolled.
https://en.wikipedia.org/wiki/The_Parallax_View