Tell her that she will become very poor and that no one will hire her in this economy, even with a degree. But if she does, she will become very intelligent and a little wiser through college experience!
tell her she will probably get an education that will make her more independent so her chances of finding a nice construction worker to fetch beer for will get pretty slim she will be more likely to find some high paying business man that will have a securary that he will cheat on her with and she will be left in some big house by herself and have to take her own SUV to the grocery store and you get the idea it's just an all around bad idea to further your education
It can be good or bad. It depends on what reasons she's going for. If she's going just for the social experience, then she may as well just join a Community College. It's cheaper. If she's going to get a degree for a career, it's not fair for you to hold her back. It should be her choice, not yours.
dude what you're doing is selfish because I only bring people down if they deserve it, don't drag your girlfriend down, just go with her because even if you don't have money for it, you can get a loan from the government or even a trust-fund