Because we see a small part of their lives, jaded by bias and slander through the media to make everyone worse than they really are. Endless tabloid magazines and rumors circulate about people we can only think about, not really meet or understand. Their motives are impossible to understand and are portrayed inaccurately, we don't know what else is going on in their lives, and we treat them inhumanly, because we only see those who we really know as human. Humans have lives and intentions, dreams, ideas, loves, hates, while these icons of industry and mechanization are merely figureheads for a normally faceless corporation. We call them idiots because we, by nature, like to feel superior, and everyone who relays the information knows this well. A magazine cover talking about how awesome the president is and how he is doing a pretty good job considering the situation CAN NOT COMPETE with another next to it talking about the latest scandal in DC.
The world is run by idiots because that is how we see them.