In a previous life, I worked as a computer programmer and I met a lot of really smart people. They were so smart in fact, that they understood 1/10 of the computer system. The computer system, a fairly sophisticated firewall, is just one of many developed at that company. There are thousands of companies like that one and they all have lots of very smart people who only understand fragments of computer systems. Work one day as a programmer and you will be humbled.
The danger in being smart is that you are relatively smart. You understand lots of simple things, you excel at many more simple things, and people count on you to get simple things right. People don't realize that you are only good at simple things, because what is absolutely simple is relatively difficult (i.e. smart people find it easy, the average person doesn't). The reality is that an extremely smart person is incapable of fully understanding a moderately sophisticated computer program. This should paint a clear picture of the limits on human intelligence. Maybe we'll learn some humility when Big Blue puts the smack down on the next Kasparov.
Society is far more complex than a computer program. What chance does a really really smart person have to figure out society if they can't figure out a computer program? Absolutely none. There is too much information and too little ability to process that information. Humans as a species just aren't that smart.
Here lies the problem with smart people. Because we perceive their intellect to be higher than it really is, we trust them too much. If some idiot came along and proposed a grand scheme to make over society you would laugh him out of the room. But a genius proposes the same stupid idea? Let the genius run with it...he must know something we don't know..he's a genius! Beware of geniuses bringing solutions, they're only human.