"year or two learning CS on their own"

Sorry, but what they are teaching themselves is not Computer Science, it is programming, which is a tiny subset of computer science or even slightly outside it but intersecting. To get a well rounded knowledge of fundamental things, such a program and data structures, memory management, analysis and design, architectures, how OSs work, cryptography, machine learning, networking and functional programming etc, takes a degree course and possibly a masters or even PhD.