Ok so i was really unsatisfied with my previous answer to you and i'd like to answer a bit more in depth. I of course can't guarantee that my answer is 100% right but it's what I've observed over the years of asking myself the exact same question as you. The thing about being uncommon is that it comes in many shapes and forms but I'll really just explore two because i don't think i understand the others well enough to elaborate on them
-The first example of an extraordinary person is that of a person who excels in one particular area and then uses that to fuel the growth of the other areas of his life. For example a successful artist
Straight up, the reason why people are satisfied with being average instead of being like this is because they are weak. they are weak and being an exceptional person is probably one of the hardest things you could ever do, it will literally take something from you . First off, achieving greatness takes drive. Everybody starts out with drive when they set out towards a goal but the thing is that success usually comes very very slowly. Basically, in my eyes success is a race against the clock. Your drive and desire to push on is like sands falling in an hourglass, when the sands run out, you quit. The sad thing is not everybody seems to start out with the same amount of sands and to be honest with you I have no idea why. Then there's the fear. though it kinda acts the in the same way as the loss of drive, I find that it can be the most devastating. Imagine that you're 29 years old, you've been trying to achieve your goal since what seems like forever and you've stopped believing that you ever will achieve it. That's when the fear sets in. It's the fear that you will die without ever knowing success or happiness. You start looking at the people around you that are living regular lives and they seem happy, they call themselves successful. You start thinking "that doesn't seem so bad" and that's when you finally call it quits. The last deciding factor that i noticed is the strength of the desire and I see how it could be categorized as a persons will to succeed (drive) but i believe it is something entirely separate. When you want to achieve something, you have to truly want it and the bigger the goal, the bigger the desire needs to be. If you want something as big as leading a life of greatness your going to have to want it more than you want many other things. that includes fun, friends, sleep and sometimes even love. Not many people are capable of desire that is greater than these comforts and again i sadly don't know why that is.
The other example of an extraordinary person would be that of the person that lives atypically, for example a man that chooses to live his entire life traveling the world on foot.
The factor are pretty much the same as the previous example except for the fear. There are two types of fear when living like this, one is the fear of missing out on what others have and the other is the fear of straight up death, which is very real when living alternative lifestyles. Sorry if this one is a bit short but i feel that many of the factors are similar to the previous example
And as for why people seem so obsessed on going to a "good" college, well I personally think It's because they have been told their entire lives that that is how they will achieve their dreams (and it sometimes can)
I just wanted to add that living the "American dream" does not at all mean you can not be an extraordinary person, it does not mean you can not be happy and it does not mean that you are settling for something lesser. In fact if you are satisfied with that life, i consider it a blessing. I know that I'll never be satisfied with a regular life and it drives me mad to think I might never know the happiness that you guys have.