It can be true that most programmers working in C or C++ are spending most of their time solving real problems that are still most effectively solved by C or C+

It can be true that most programmers working in C or C++ are spending most of their time solving real problems that are still most effectively solved by C or C++, and at the same time, that even the absolute top C and C++ programmers regularly misapprehend UB itself or whether their own code contains UB in a way that causes a serious issue for the program.