If you're productive in Node or Python, then learning Ruby would just be educational in that it's something else to use. Personally, I've found Ruby to be a great language in which I can be productive quickly, which is why I stick with it, but I've written Ruby code off and on for the last 15 years in various forms of production code. I think it's great to learn, but I wouldn't switch to it (or anything) if you're already productive elsewhere.