In my personal experience, I find that those who are smart and educated to be more arrogant than others. If you've ever tried to have a civil discussion with someone who is "educated" or book-smart, you will know what I mean.
I wouldn't say I'm "smart" or that I know a lot. Then again, I only have a high-school diploma. One day, I want to go to college, but that's likely to be in the distant future. I hope that once I have received my degree, I won't lose my sense of humilty. I think it's fair to say that most people are generally smart. Some are more street-smarts than book-smarts and vice versa. I think in general there is a lot people don't know and will likely never know. I think a lot of people think they know something they don't really understand (myself included).
I think if most people were truly on the level of smarts they only think they are, they would be mind-blown!