The reason why JavaScript has succeeded where many other languages, whether statically typed or not, have failed, is that it was bundled with a runtime platform

The reason why JavaScript has succeeded where many other languages, whether statically typed or not, have failed, is that it was bundled with a runtime platform - the web browser - that became ubiquitous. Millions of people want to write programs that runs in a web browser, and it's easiest to do that in JavaScript. JavaScript is a textbook example of "worse-is-better", and you are right, for compatibility reasons we are going to be stuck with it until long past its best-before date, just like C.