While it's good practice to have a bit of an idea where you might like to go with your degree, university/college is an opportunity to get outside of your comfort zone and explore many different options. Most people I know changed their mind about what they wanted to do for a career from the time they started their degree to the time that they finished.
In addition, you have so many opportunities available to you while you are in school that you may not have access to otherwise. Try volunteering at different places on campus, go to the campus career centre and learn about opportunities through them, join student clubs or organizations. These are all ways to better determine your interests and if you would really enjoy working in a certain career field rather than just attending classes alone.
University/college can absolutely be expensive, so if you decide to go then make the best of the opportunities available to you while you are attending school.