The world is too complex for a small cabal to be controlling everything. This complexity is difficult for our puny minds to comprehend, so we instinctively latch onto simple models with a Wizard of Oz at the center, pulling all the levers and pushing all the buttons to make everything work the way it does. The ancient Greeks thought Zeus and the other gods on Mount Olympus controlled everything. The modern mind turns to secretive cabals. Same idea.