It also includes people wanting to write standards-compliant code, and even "people who want to contribute to compilers." The closed nature of the standard means secondary sources dominate my search index. A previous rant about how the entire internet fails to warn you that atoi("a"); is undefined behavior: https://news.ycombinator.com/item?id=14861917

I've contributed a few patches to rustc, shipped multiple C++ projects, and even technically submitted a patch to LLVM. I've got a copy of the C++03 standard... but even I haven't rushed out to empty my pocketbook for C++11, C++14, C++17, and C++20, despite using them.