Universities should be more than toll gates

The elephant in the room here is that perhaps the biggest difference between the two learning experiences that OP is describing is himself.

He might just have discovered he is more mature at 30 than he was at 18...

There is a difference between learning about things that you find interesting at your own pace, and learning about things that interest other people with tight deadlines. Even if I enjoy learning, there were absolutely courses that were just a waste of time.

> Even if I enjoy learning, there were absolutely courses that were just a waste of time.

My university experience is somewhat different, and I believe whether this holds true or not depends a lot on the degree course:

- In mathematics, there are barely any "filler courses". Basically all of them were interesting in their own right (even though because of your own interests, you will likely find some more exciting than others).

- On the other hand, computer science more felt like every professor had their own opinion how the syllabus should be, and the hodgepodge that came out of it was adopted as syllabus (design by committee). Thus, there were quite a lot of interesting things to learn, but also "filler courses". Additionally, the syllabus did not feel like a "consistent whole" with a clear vision, but rather like lots of isolated courses that you had to pass.