[mortylen]

As already described, it depends mainly on what you enjoy, so that you don't get tired of learning new things. As far as the job market is concerned, knowing only one skill is not an advantage, it is best to excel in a certain combination of skills. And it seems to me that Rust and Machine Learning go together. You can learn the basics of Rust quickly, especially if you already know other languages. How quickly you can understand ML, I don't know, it seems to me to be a very broad term.