I am in my fifties, a software engineer, and I am enrolled in a masters program for mathematics and really learning at a ferocious rate compared to my job, where I can alternate learning with using what I've learned.
For me, learning a lot is very worthwhile. Not everyone shares that goal for education of course.
That last sentence sounds snarkier than I meant. For instance,for all my classmates they are enjoying the learning and also trying to make a career out of it somehow. Different altogether than my fun based curriculum
The real answer? You gained a piece of paper which certifies that you are educated in a field.
Depending on the school you may also gain access to an insular professional network.
That's pretty much it. The notion that university degrees are worth anything more than that is moderately outdated.