Of course not. But when you finish implementing Forth, you'll know how to implement forth, but not much else. But once you build a parser, you'll know how to build a parser for most any language. You don't have to learn every sort of parsing technique; I only use recursive descent. And once you learn for to do data-flow analysis, you'll find it applies whenever you want to write an optimizer. Same for various optimizations and code generation techniques.

Indeed, I'd argue that Forth is best appreciated after you've worked on other compilers for a while. Then you have a basis to appreciate how clever it is.