I think there is such a thing, but they do not rule any country or location. The thought of them doing such would be idiotic, as there is such a thing as leaders of different religions than the theory of satan. There isn't just one religion, meaning that in order for the illuminati to have any ruling power, they would have to change the religion of hundreds of millions of people.
Those who are illuminati would most likely be schizo or carry a disorder which leads them to become something of an evil character. There arn't that many fucked up people in the world. It's just that the fucked up people who do exist emphasize their power and strength. A great example of this is Hitler. He didn't start off with hundreds of companions, he just acted all strong and tough in order to gain them.