You think a diploma won't help you out in life, and honestly, it may or it may not. But the idea is that having a diploma is a kind of job insurance. Just like we all have car insurance to take care of the "what if..." circumstances, we don't intend to get into car accidents, but as many have pointed out before, we never know exactly what life has in store for us. If you were in your first year, I would be telling a slightly different story, but you're almost there. To quit now will not be a testament of strong will (ie fighting the social pressures), but rather you will be a "quitter"-- nothing else.

As to the social situation, I am quite introverted myself; I was really nervous about moving in with random people when I came to college, but I realized it's actually quite an amazing experience. Once you're in the right environment (ie with other people your own age), you'll be able to discover that college has another side to it; there ARE parties, there ARE people, and at that, there are many really friendly people out there.

And.. if your parents are paying for your tuition, then you should finish out of respect, because then that would be three years worth of tuition that they invested in you, and you would just be an ungrateful kid if you dropped out on them. If you have been paying for tuition all along, then this truly is your own decision, but think really long about this; it's a major decision.