University art programs and art colleges today do not teach you to paint - they attempt to teach you to be
articulate about your work.
Not a bad thing, really.
Some courses of instruction are more valuable than others, but even in the most valuable classes you still teach yourself to paint. You paint with your brain even more than with your eyes.
I don't think we can compare the historical Beaux Arts education to our present degree programs. Many of the artists discussed on this forum had at least some exposure within the Beaux Art system.
It's not where you learn something. It's what you learn. Anyone attempting a painting career should be open to all the culture around them and a university education is very good for that exposure.
As mentioned previously in this thread, just showing the tenacity to complete a degree program tells the world something about you.
For those reasons, I'd vote to finish the program.
Another suggestion: Talk to the faculty. Tell them what you want or offer to give a class. I expect any art faculty would be delighted to find a serious portrait oriented painter who wants to increase his/her knowledge of that subject. My recent experience in college is that figurative and portrait study is now accepted and desirable.
Also, I agree with many others here who have suggested you attend specialized portrait courses. You can do both, maybe not right now, but you are young. You have time.