If you have a very deep understanding of C++ then you are potentially yourself a good reason to start a project in C++ and this statement is true of any languag

If you have a very deep understanding of C++ then you are potentially yourself a good reason to start a project in C++ and this statement is true of any language. Knowing the language very well can mean more time focusing on the actual goals and less time messing around with incidental language things. C++ is not sufficiently bad that mastery of it doesn’t trump other concerns for personal projects. Even in companies you are often likely to find more C++ expertise than Rust expertise.