Like I said with some very poor grammar on another answer. Book smarts only gets you so far. Regardless of education levels anyone can survive life. Whether you dropped out of high school. Or have a Doctorate from Harvard. If you have no street smarts or common sense and can't learn from your mistakes. You will have a very hard time making it through.
One of the prerequisites of being stupid is being unable to understand your own incompetence. If you can learn from your experiences and adapt yourself to your environment, you are intelligent. If you consistently f*** up the exact same thing a few times in a row without trying anything new, you're an idiot.
Yea a lot of times people who are real smart bookwise don't have real good common sense. Its just one of those things. Its not true for everyone but I know quite a few people like that. Don't really know what to do to fix that though.