University is not just "bigger school". It gives you the time and resources to dedicate yourself to study. If you just want to write programs then of course you don't need uni. I could write programs before I went. In fact, I earnt money from it before I graduated, making me a self-taught professional programmer too.

What I came out with was a far broader picture of what's been done in computing and, more importantly, how to find and read information about it. The biggest difference between me and my colleagues who haven't been to uni is when they run across something they haven't done before they are completely lost, whereas I'm usually able to say "hmm, that sounds like a graph problem, I think there's an algorithm for that".

Having said that, what I didn't come out with was how to do testing, version control, CI etc. Luckily that stuff is easy to learn on your first job.