📝Java is popular because of marketing

Sun has spent an enormous amount of money marketing Java (e.g., Sun preps $500m Java brand push • The Register). They even had Spy-themed Java commercials (Sun Microsystems The Spy Java Commercial - YouTube). That might explain why Java became popular.

Languages become popular when they bring innovative runtime argues that Java had an innovative runtime at the time. There were just a few languages that had VM, garbage collection, and static type system—and these are valuable enough properties so that the language could become popular.