Part of the answer is in term C/C++ itself. C is a very popular language because the history around Unix and FFI. C++ builds on that popularity by being sort of backwards compatible with it and being what Microsoft Visual C++ supports if you want more languages features beyond ISO C90. Which brings to mind another factor, that people used to pay for compilers and IDEs. The hobbyist had to consider price as well as functionality, portability, performance and popularity in what programming languages they choose. Given there were several C++ compilers to choose from and the popularity of Windows it makes sense that C++ won.
Why has nothing replaced it? That depends on what you mean by replaced. Python, and Typescript/JavaScript have replaced it in many places. It's just low level programming where C++ has yet to be superceded. For that kind of programming there had not been many that could even approach the space until LLVM-based languages started coming out recently.
Some things come down to the OS system. We're still using the C FFI and other system elements designed around C. So until something better replaces those we're still using C on some level.
Why has nothing replaced it? That depends on what you mean by replaced. Python, and Typescript/JavaScript have replaced it in many places. It's just low level programming where C++ has yet to be superceded. For that kind of programming there had not been many that could even approach the space until LLVM-based languages started coming out recently.
Some things come down to the OS system. We're still using the C FFI and other system elements designed around C. So until something better replaces those we're still using C on some level.