The problem with C is that even a C master can't necessarily write correct code, because C is a very programmer-unfriendly language, making developers remember to do various actions manually and perform error-prone calculations.
C++ is definitely harder to master (after many years, I can't say I master every corner of the language), but it's much easier to write correct code in C++ and it will be just as fast, run on as many platforms, etc, etc.
C lost this battle a long time ago, it's surviving because of nostalgia, still having good street cred and inertia. The number of domains where one must use C is shrinking and now that we also have Go and Rust this will accelerate. All for the better, really.
