"Taking advantage of my location in Cambridge, I have sat in on some classes at MIT in Atmospheric Physics, Biology, and Geology. I also teach a software engineering lab course at MIT every three or four semesters (textbook). But for me, the university has mostly been a source of entertainment; I have never looked to it as a source of income."
http://philip.greenspun.com/careers/women-in-science (Appendix E)
So the compelling reason might not be that getting a degree will impress other people, but that learning is a fun and enriching experience. Yes, there are dead trees in libraries, but lectures, being able to ask questions to someone who is an expert in what you want to learn, and collaborating with peers who also want to learn are difficult to duplicate with only dead trees.
CS is a brand-new discipline, which means it's in the process of generating a lot of shallow observations right now [1]. In another generation or two, some brilliant synthesizer will come along and produce a real theory. For now though, most of the stuff you learn as a CS undergrad (other than a few senior-level theory courses) should be obvious if you know how to program.
If you do go back, pick another discipline and study it like a computer scientist on vacation. Pick ONE powerful software package (python might be good, or maybe (sic) Mathematica) and use it to do ALL your assignments. Focus on simulation and visualization. You get to learn something real, and you get to do cool software work at the same time.
[1] Graph theory is almost 100 years old now, and we're starting to see the discipline collapse into a hard core. You still need a lot of loose terminology to get started, but after that there's a clear progression through the different concepts.
By leaving college I was able to get rid of a humongous stressor in my life, and this new mental freedom let me pursue my interests and study what I liked. Now I've figured out how to actually sit down and study, and I could actually take an interest in all the GenEd courses that pissed me off so much in the past. I bet now I could go back and actually finish an undergrad degree with good grades... but now I need it even less than before; I've learned how to study on my own. If for some perverse reason I do end up going back, I'll probably study math. That's one area that I'm still figuring out how to self-study.
http://www.math.uni-hamburg.de/home/diestel/books/graph.theo...
I don't want to work for someone who places such an importance on having a degree anyway. I want to work for someone who hires me for my ability to do work, so I think demonstrating that ability to do work is more important than getting some piece of paper.
A Bachelor's degree is just a certificate of minimal competence anyway. A significant fraction of people with BS CS degrees can't even write simple programs. There's plenty of other ways to demonstrate minimal competence than to get an undergrad degree.
So, anyway -- why's it so important to have a degree? Everything they teach (and much more!) is available in the form of dead trees at my local library. I can party with my friends regardless of whether I'm in college or not, plus now I can afford awesome beer. What else is left?