It is a fact that people still do graduate from C to C++, for a wide variety of reasons. Some discover that their embedded system can be coded with C++ as easily as C. Some learn that C++ is faster than C. Some just gain more confidence and adopt a new feature that is only in C++.

The large number of remaining C coders, and the ease of switching incrementallty, means that the number switching to C++ is always overwhelmingly larger than the number adopting Rust from all starting points.

We may lament that they do not start writing modern, high-level C++ immediately, but the number of CppCon (and similar) talks hosted on Youtube, and rocketing attendance at, and number of, such events, shows that there is great interest in learning good modern C++.