I've always debated this with my college-educated buddies. Most of them confuse intelligence with knowledge, but the two are not directly correlated. Yes, intelligence makes getting knowledge easier, but my experience has been that you don't have to be smart at all to finish college, just good at applying yourself over a 4-5 year period. What I've seen overall is a person who is driven will make WAY more money that someone that just gets a degree to get a good job. And hard work goes along way in the corporate world as well. This obviously applies to general application jobs, not specific training jobs like an attorney, doctor or upper level engineer.
Taking a cross-section of my friends who are all about 35 years old, I have three friends making over $250K/yr, all have four year degrees, and nothing more but incredible knowledge of investing and an entrepeneurial spirit. I have a few friends with four year degrees making less than $40K/yr. I also have 3-4 friends making very good incomes without a degree, but not as good as the top three. And my wife manages $12 million in annual business in her stores and manages 80+ people, no degree whatsoever.
I don't have a degree either, but I'm in the car biz, so I don't make shit.

Although my business has doubled each year over the last two years and is already tracking to repeat that again this year. And then there's my other two businesses.
