1. full understanding of computer architecture, realizing how the CPU executes code
2. analyze efficiency (Big O) (a few hours), knowledge of advanced algorithms
3. understanding compilers
4. knowledge of the OS workings (often self taught out of necessity)
5. AI fundamentals (Admittedly a specialized topic)However, some self-taught people have conditioned themselves to hate CS due to constantly needing to prove to companies that they are qualified for a job despite not having a CS degree. These people place little value in understanding CS and because of that they are worse off because they weren't forced to learn it.
It all depends on what kind of person the developer is, and I am glad that you are the first kind. I'm getting tired of HN bashing any article that suggests that perhaps a developer doesn't know everything.
There is one way in which I feel handicapped compared to my colleagues, which is that I find it generally hard to grab a book on a programming topic and read it cover-to-cover (The same goes for taking classes). I've got to get a development environment up, see how I can break the 'examples', and generally abandon the book to doing my own thing before I get more than a third of the way through.
On the other hand, every time I've worked with more classically trained developers on real projects (and all the cruft that goes with it), I always find that there are corners of the code base that none of them understand, and no one ventures in to find out what's wrong.
Myself, I need to understand how a system works in order to work on it, so I always dig, and tweak here, or tweak there, and so I tend to learn full systems much quicker than my colleagues.
In the end, it's a trade-off, but it's how I work, so I guess I'm stuck with it.
In all honesty, I can't say I know for a fact that knowing these things made me a better developer. It's hard to quantify. In your day-to-day life you don't generally use such knowledge. It's entirely possible that it didn't make any difference to my actual work. I certainly did use it during job interviews and lunch-time conversations with my coworkers.
What a shame. There are lots of very accomplished self-taught people who know much of this stuff and are busy changing the world. I sincerely hope you get a chance to meet many of them.