Really, no one's forcing you to write it. But if you have a working understanding of JavaScript and you can't read CoffeeScript fluently, it's because you aren't trying. Just swallow your pride and deal with it already.
Come on, what kind of percentage are we talking about here? Tiny. Absolutely tiny.
Take ten minutes right now and read through the CoffeeScript reference-- poof, you learned it. It is just JavaScript.
Well, you haven't learned it unless you memorised absolutely every aspect of it, which you're unlikely to do on a first read. And it isn't "just" JavaScript- it has significant whitespace, different object notation, etc. etc.
Don't get me wrong, I've started using CoffeeScript and I like it. But it's a tiny, tiny minority language. There are a ton of JavaScripters out there that haven't learnt it because they don't need or want it. That's their choice.
Oh man!
I guess I don't know any programming languages whatsoever.