Secondly, C/C++ is like the third or fourth most commonly listed programming language in job listings. If you think all but 2 or 3 languages are niche, that is not what the word means.
Most software problems are not about solving them faster, it’s about combining existing components in new ways and figuring out to orchestrate it all.
I don’t care about copy elision, heap fragmentation, perfect forwarding, when my performance is being lost in the communication between services. What I need is a better architecture and more scaling, not concerning myself with if this loop is being vectorized, or that object is being moved instead of copied, and other minutia which inevitably ends up wasting your time when writing C++.
Niche does not mean "stuff I don't personally use at my job", but that is the only definition under which Typecript is not niche and c++ is. C++ in 2019 had the 4th most job listings according to Indeed. Calling that a niche is absurd especially in comparison to Typescript.
There are also many places which just ask for Java/C++ experience for no apparent reason. Amazon is like this, all of their job listings mention C++ but only a very small percentage of the code base is in C++. There is at least 10 times as much Ruby code and it is part of systems that most engineers will have to work with, but no job application mentions that.