You know, I worked very hard in college. When I graduated, I graduated valedictorian with a 4.0 and I was very proud of it. After my first year in the industry, I applied for a couple of positions, and during the process of interviewing for those positions I realized that even just a single year out of college… nobody cared about my 4.0 anymore. The only thing anyone wanted to talk about was what I had been working on for the last year. The year I hadn't been in college. I felt a little betrayed at that point - like I wished someone would have told me how quickly my degree would become “useless”.
But here's the thing I didn't understand yet, and the thing you need to understand now. The video game industry is chaotic. Projects come and go… and with them, so do developers. It is very common for employees to be picked up on a contract basis for the sole purpose of getting a single project out the door. It is also not uncommon for a project to finish (either successfully or unsuccessfully) and large numbers of the people who built it to be laid off. The elite programmers in a studio are not frequently affected by this turnaround… but the weaker programmers in a studio definitely are.
Game development is hard. Many of the people you will run into are both incredibly talented and incredibly passionate (read: they put in a lot of hours on top of having a lot of natural talent). In the past, I have encouraged people to realize that a college degree doesn't make you an expert on anything. In comparison to the rest of the developers already working in the video game industry, it makes you an absolute beginner at everything. As a new developer (who hasn't even finished college yet), you will almost certainly either land at a studio that is not large enough to be relatively stable, or become one of the weaker programmers at any studio that is large enough to be relatively stable. I say this to drive home the point that unless you are a true wunderkind, you will spend a lot of time at the beginning of your career applying for jobs.
As a personal story, a friend of mine (who also did not have a degree) once applied for a job on my team at Electronic Arts, and several weeks later I finally directly reached out to our recruitment team asking why we had never seen his resume. Their response was, verbatim: “We haven't sent you his resume because this is not EA University.”
The combination of these realities is why you want the degree. Without any work history under your belt, your college experience is literally the only thing that recruiters and engineers on a team have to look at. Do you want that experience to read: “I couldn't be bothered to finish college”?
You should also consider worst-case scenarios. What happens if you discover that you can't get a job in the games industry right now, and have to take some other work for a while to make ends meet? That general CS degree gets really valuable in a hurry. Your college degree will not be very useful for very long. But during the phase where it does matter, it is the single most important thing on a very short list of things that matter.
You should listen to kseh and also make some games while you are finishing school. This will both scratch your itch, and it will also make your technical interviews fresh out of school go much more smoothly. Imagine what happens when you walk into an interview and the interviewer sees an actual finished game on your resume. Now he can ask you a bunch of direct, relevant questions about problems you've already solved! You don't have to figure much of anything out on the fly, and you nail every question he asks. Do that. It is the second most valuable thing you can do to break into the industry.
But it's still the second most valuable thing you can do to break into the industry. The most valuable thing you can do - to break into this specific industry or do anything else with computer science - is listen to Tom. Finish the degree.