The reason I generally don't believe in conspiracies is because (1) people are shit at keeping a secret, (2) incompetence is widespread, (3) parallel behavior is far more common and appears identical to organisation, ...among other reasons.

Maybe you are right.  But when it comes to professional agencies that specialize in this stuff and have a proven level of competence in it, then I do believe in conspiracies.  A small CIA team of highly trained morally bankrupt sociopaths using nearly unlimited government funding can be a lot more successful than your Bohemian Grove or Skull & Bones or WEF group can.