Better question: how much are you spending on university vs. how much you would be making not going to university. If you are taking a lot of debt and have a decent job if you did drop out, then it might be worth taking a year off to try it out. On the other hand, if you would probably just be unemployed and playing video games most of the day, then you should probably stick with it for a bit longer.
It's not all about money though, one of the reasons I'm going is just a desire to learn more about a specific subject (physics)
Its great to have a genuine interest in a subject. Unfortunately, for a lot of people, the cost of going to school solely for what they are interested in may be too high to justify. It's one thing to take on $300,000+ in debt if you doing an MD, its another if you are doing an MA in Poli Sci.
Besides, nowadays, you can get almost all of the information you would pay to learn in a BA for free online. So the main thing you miss out on are the facilities and communication between your peers, which may or may not be important to you if you would be going just for interest's sake.