First comer advantage. Initial Java was a robust, yet simple, sane build tools, relatively safe, typed language when most everything else was c or c++ and not as "safe" (modern c++ is actually very safe language if you stick to its guidelines however). Over time Java has become almost as complicated as Modern C++ but people picked it up over time mostly. It's still used because it's still a robust general purpose language, tons of libraries, huge corps don't like to rewrite things, and there are lots of Java programmers out there. Don't let the webstack blind you, there is a whole other world out there of backend, embedded, finance, and legacy stuff that hackernews audience is just a small part of.