I got into development from doing design work, also self taught back in the 90's. I wanted to do something... spent a very rapid weekend learning JS from a very large book, then applied what I needed the next monday. Spent the next weekend finishing that book and the next month swallowing three other large books on the subject (two more on JS, one on HTML). From there was VB5 then Access & VBA... then I started working as a developer. From there I learned more about databases and data structures, dabbled in C/C++ then circled around to VB6 when it came out. From there around the end of 2001 (after 9/11) I was unemployed and no jobs to be found. While crashing at a friend's house I learned C# with the command line compiler and another large book (didn't have VS). Since then more databases and db types, more C# and when it came out Node.js (had done a lot of classic ASP in JS along the way too).
I spent about 5 years working in eLearning, writing simulations of systems for learning/training as well as courseware. Really enjoyed that time in my life as I was constantly taking in domain knowledge as well as a very varied environment. Unfortunately after a while all the context switching and constant intake took a toll and I took a few more boring jobs doing corporate/banking work.
In any case, you'd be surprised how much you can learn without a formal education, or anything really structured at all. To this day I tend to take in new stuff rapidly and get bored once I've figured out the hard parts. Currently working on learning Rust and Kubernetes, short break on rust as the async syntax gets implemented and settles in.
But to respond to "self-study isn't nothing": that's true, but your self study didn't replace college, it replaced self study. What I mean is that everyone has to do that self study and job training targeted at the specific stuff they're doing. Self study is necessary to expand "known knowns" in targeted areas, which is really necessary. It's just not as good at illuminating "unknown unknowns" as a curriculum put together by a person or group of people who know the breadth and history of a field.