An irrelevant degree takes some years that you could invest into a working experience, and more importantly, it delays maturity. But it can give you a valuable knowledge (of course, if you earn grades for real things, not for imitating some nonsense). This is hard to learn in everyday life.

I program in Python and earlier was a DB developer, but have an economics masters degree. The most useful thing of this degree was maths and games theory that surprisingly comes to conclusions on things like morale, honesty and dignity, and shows that they're not relative as the classic economics implies.