Have there been conspiracies involving 2, 3, maybe a dozen people throughout history? Undoubtedly.
Are there conspiracies that would require hundreds or thousands of people keeping their mouths shut for decades, as would be needed for the wilder conspiracy theories related to 9/11, Kennedy assassination, etc.? Not so much.
Agreed. The moon landings are a case in point
As for ad hominems, that works both ways from what I've seen. "Sheeple" or "shill" aren't compliments and anyone who's played these cards and points fingers is just a plain hypocrite or has a masters degree in self deception