If you go into it as a means to an end, then yes, it probably would be a waste of time. But....if you actually approach it as an opportunity to expose yourself

If you go into it as a means to an end, then yes, it probably would be a waste of time. But....if you actually approach it as an opportunity to expose yourself to new ways to think about problems, I don't think that would ever be a waste of time. I disagree that you'll never use C idioms in C++ or Rust, but even IF that were true, there's absolutely no way that having a better understanding of what the underlying hardware is doing is a bad thing.