I can
honestly say I encountered this same
disillusionment when I graduated from
UIUC. For both of us, the
reason seems to be the same: the people around us and
society in general treat a college
diploma as a major accomplishment, while the actual
graduate knows that it really wasn't all that difficult. (Note: This is a local
truth, not a
universal one. Moving on.)
Speaking personally, I coasted most of the way through university classes on my natural smarts. I say this humbly. In high school I was an introverted academic, took a wealth of AP and honors courses, did well in them, and then headed off to a state university. But by the last semester of my high school career, I was tired of it all -- the studies, the grades, the self-motivation. I'd been accepted into college; wasn't that what I was getting all these grades for?
In college, then, I stopped pushing myself, mainly because I didn't really know what I was pushing myself toward. I was going to get a mathematics degree, yes, but I wasn't really sure why. Eventually, I just finished off that degree as quickly as possible and headed into web development as a career instead (and I will be forever glad that I did so).
I think that a sense of accomplishment is a product of two things: how hard you motivate yourself, and the meaningfulness of the goal achieved. Today, a B.A. or B.S. isn't as distinguishing as it used to be; nevertheless, it's the result of a huge investment of time and money, and it is a big accomplishment. It's only not when you compare it to the work you'd have to do to educate and feed yourself without one.
If you're looking for a true sense of accomplishment, I suggest focusing on the next big goal of your life: getting a job. Spend some time deciding exactly what you want to do, and after that, where you'd like to work. Maybe you'd like to work for a big-name game developer? How about a startup in Silicon Valley somewhere? (Whatever you do, though, don't apply to Microsoft if you want to regain the feeling that you're doing something useful.)
Whatever it is, make sure it's someplace you'll be happy for several years. Then research the company. Then study and practice your interviewing skills. Then figure out what salary you're really worth. Then go out there and, goddammit, GET THAT JOB! And after you've been there awhile and proven yourself, you can figure out what you need to get your first promotion and start the whole cycle again.