Wow, that sounds pretty intense. It's probably a complex interplay of temperament and world view. I admit I don't really have a clue how to broach it.
I think I would probably try to find whatever germs of positivity I could and then work from there. What are her passions? Are there things that she loves doing? What makes her really happy? What sorts of things does she deem profoundly worthwhile? If she found out she only had two weeks to live, what would she want to spend that two weeks doing? Does she have any ethical or spiritual beliefs that stray into hope or faith or a belief in goodness? Are there people or professions or charities or movements that she hold deep admiration for?
If I could identify some of those positive things, I'd do my best to get her more immersed in them. Of course a lot can change in three years, but I agree with you about her college prospects, at least if she remains in her current mind-set. College is an expensive and time-consuming endeavor, and I think young people should have a pretty good reason to pursue it, one that goes beyond "A degree might get me a better job and at least I wouldn't have to think about working and supporting myself for another four years."
If there are any other red flags for depression, anxiety or other mental illness, I think I would initiate some sort of psychological care / counselling. She could be engaging in "displacement," blaming outside circumstances and others for things that are too difficult for her to face.
On the other hand, in the absence of such red flags, and since this seems to be a pattern going back several years at least, I wonder if she's simply formed the habit of using blame of her external circumstances to avoid taking responsibility for herself and her own experience of the world. She may need a little "tough love" to push her into taking responsibility for creating her own environment and conditions for success. Rather than allowing her to shift all the negativity to things outside her, challenge her on her attitudes. When she sounds off, say things like "Actually, I really like Stephanie. She's kind and she thinks of little details that help put people at ease. Yes, she's naive, but she's honest as anything and wants the best for everyone." Or "Sorry, chemistry is NOT stupid. You are just frustrated with your homework. You can choose to blame your frustration on chemistry itself, or on the course or the teacher, but I bet there are kids who think chemistry is awesome and who are enjoying the course. If you don't, well, it's your attitude, your choice. You could choose to look at it differently."
Is there any way you could afford the time and money to give her some sort of world-view-altering "coming of age experience?" When my eldest was almost 15 we sent her off to the third world backpacking with some neighbours of ours for three months. It blew her world open, sleeping on straw mats in bamboo huts, playing in the river with joyful little kids from incredibly poor families.... My ds has been volunteering with a local computer-access group, mentoring people in the school and community on tech-related stuff, rebuilding computers for community use, fundraising and donations. Giving something to others and developing an appreciation for the advantages you enjoy compared with many others, I think those are crucial parts of maturing.
I dunno. My 15-year-old seems like he's your dd's polar opposite. He's almost too optimistic, too welcoming of everything and everyone. It has its own problems -- naiveté and social recklessness among them. But at least he seems happy and excited by his life and the world around him. It must be hard to watch your child grow up feeling unhappy about the world she's surrounded by. I hope she can find something that really excites her and move forward towards it. That would give her a sense of purpose, which would be reassuring as she moves towards adulthood and possible post-secondary education.