Are you looking to do anything that would benefit from it? AIUI, C# is a perfectly good language, especially in the Microsoft ecosystem. Don't get me wrong, broadening your horizons is good, but I would hesitate to learn rust specifically unless you really need to do something low level (whether because you're getting close to hardware, need no GC, need very precise memory control, other performance reasons...), target a platform that rust works on and C# doesn't, or want to use a library that's available in rust, isn't available in C#, and can't be surfaced to C# with minimal FFI wrapping.