Forgive the slightly disjointed metaphor, but the publishing business is sort of like a train.
You've got to have that engine--your first marketable book that actually takes you somewhere. But if you want to have a career in publishing, you can't stop there. You've got to keep adding to the end of it. Put out another book while you're working on the next. And have the outline for the one after that. Think of them as cars on your train...and you want that train to be as long as possible.
But again with the train metaphor--it's going to take a while to get up to speed. That "engine" is going to take a year or two, maybe longer, before it actually gets moving, and by then, you want to have a whole series of cars behind it.
The way most writers handle this is by writing that first, important novel while they get their financial support from elsewhere--a day job, their parents, their spouse, whatever. Who can afford to spend months banging out a novel, then wait a year or more for it to start making any money?
But there are two things to keep in mind. One: the vast majority of those authors will STILL never make enough to live on, and Two: for a novel to really be an "engine," it needs to either make enough money to comfortably support you while you write your next couple or be the one that lands you an agent and a nice publishing house, thereby opening the doors for your next novel.
If none of your self-published ventures have done either, they aren't proper "engines." And because there are no barriers to self-publishing and anyone can self publish their grocery list if they so choose, they don't count as publishing credits.
Sure, you can point to self-published novels that impressed agents...but only because they made enough money to support their authors. You really need to meet at least one of the two "engine" criteria I mentioned above. Of course, meeting both is better.
So here's my take: if you don't have that "engine" novel yet, stay in school. You're going to need a day job during the time it takes to create one and get it moving.
If you do have one, and it's already working for you, there's probably no harm in taking a year or two off in order to see where it takes you.
But even if your next book is a runaway best-seller, I still think it would be nice for you to have your degree. It looks nice in the back-cover copy, and even runaway best sellers don't support their authors for life, most of the time.