Loved this! To be honest I think the more you learn, the better for you but I would even disagree of learning everything since then you can't specialize as much as other people. I'd say, it depends on what you look for. I've seen successful people who are savvy in lots of fields but I've also came up to meet people who are really good at just a couple of things :) And I say this because I believe it's not only about the quantity of languages that you know, but also how it's gonna be implemented, a developer that knows about business is in my opinion really valuable and difficult to find.