Conspiracy theorists often postulate that our world is controlled by a tiny lump of people on top.
Pyramid shaped hierarchies don't perform as well as expected
The amount of corruption in a hierarchy will be proportional to the amount of the pyramid's layer. There will always be some contradictory interests, and everyone will lie a little bit to his/her superior and subordinate. The accumulation of lies and corruption will cause the pyramid to have very little connection between the top and the base. In other words: while the big boss's orders will be so distorted at every layers that the people on the bottom will do something completely unrelated to the original idea, the information gathered from the people at the base of the pyramid will also be so distorted that the input given to the boss will not be reliable to make good decisions. Our world cannot be controlled only by people on top. The power is diluted at each layer of the hierarchies.
Our world is far too complex to be managed by a few people
We often underestimate our world's complexity. There are so many influences and interaction. Our only brain gets a mere mental simplification of our world. Conspiracy theories are over-simplification of the inherent phenomena.
Fear induces lies from the immediate lower level in a hierarchy
When a hierarchy is too strict, it is often a matter of survival to lie to your immediate superior. (Hiding problems, telling your boss that everything is fine when it's not the case etc)
People on top compete against each others for more power
People at the top of hierarchies compete against each others in order to get on top, so they often betray each others by playing mean tricks. It is quite hard to maintain a cohesion. Everyone close to the top is avid for more power and would want to kick out the number one and take his/her place. For someone close to the top, it is quite advantageous to distort orders given by the top in order to make it serve other ends.
When you're at the bottom of a hierarchic structure, you have a unique power which is gathered from interaction with the real world. An employee at the bottom of the hierarchical structure of a large corporation will often have more freedom than his immediate superior who's "between the hammer and the anvil". We are however conditioned to believe otherwise.