[cutler]

> I don't get how other developers get so invested

That's because your investment is means-to-an-end. For others, such as DHH for example, their chosen language is a means of expression and consequently they have a very strong personal investment. The Ruby and Clojure communities, for example, largely consist of developers who have a very strong personal attachment to the language and that's understandable since these languages are much more expressive whereas a language like Java will tend to attract developers who see it merely as a tool and maybe use it because it is a market leader. Languages like Ruby and Clojure demand a broadening of the mind so tend to attract users who are looking for more in a language than the standard fare of Algol-based features.