However, a good education is much more than this. It includes the opportunity to engage in back-and-forth discussions with professors and classmates, building social and professional networks that can pay innumerable dividends, and to pursue experiences that aren't immediately related to career advancement.
College shouldn't merely be about vocational training. While that's one valuable outcome, there is much more that can be gained. Of course, many colleges (and individual students' experiences) fall far short of this—I wish I thought this way when I was in school, and didn't just see it as another hurdle to full adulthood—but that doesn't mean that the concept is flawed.
My local public library doesn't have a book on advanced logic design, for example. It favors a more 'general' collection, and thus books with heavy reliance on math tend to be omitted. Same with in-depth law books, they just aren't there.
The big distinction that ends up causing all these arguments is that when people say it's a bad decision, they mean it's a bad financial decision when you go to college and take on debt to get a degree that won't lead to a well paying job. Of course everything is about context, so it might not be a bad life choice, but the debt certainly should not be ignored in evaluating that decision.