One particularly good way is to be attached to an OS or platform.
- C came with Unix (although was so good that it migrated off it to Windows and basically every other platform).
- JavaScript came with the browser
- C# comes from an OS vendor; Microsoft. They built APIs for their platform in C#.
- Likewise, Objective C was for NeXT, and Swift is for iOS. They built APIs for their respective platforms.
- Java is an interesting case because Sun wanted the JVM to be an OS, to replace Windows, but they ended up with just a language. This is great evidence that a language itself is unprofitable; an OS/platform can be hugely profitable.
You have all the main OS cases represented: Unix, Apple, and Microsoft.
Google is sort of an OS/platform company, with Android and ChromeOS. However they reused Java in the former case. They designed their own VM (Dalvik) instead of inventing a new language. For the web platform, they are designing and implementing Dart. For the "cluster of servers" platform, Go is very appropriate.
Mozilla is also a platform company; it's not surprising that they are investing in Rust.
So my takeaway is that OS/platform vendors are the ones with the main interest in the huge effort of designing and implementing a language. How successful the platform often has more to do with the success of the language than the language itself. Java might be the exception.