In my opinion, the reason it and other languages aren't more popular is that they don't have a "halo" product that forces you to use it.

For example look at Elisp. It might be the most successful lisp in the modern Era because of Emacs. Emacs alone is like over a million lines of Elisp, and the ecosystem of packages is gigantic. A lot of people do not like Elisp, and there have been many attempts to create Emacs + a better language (Guilemacs, First/Second Climacs). But it has all failed because Emacs proper has a lot of momentum, and you can't build Emacs + a better language. You need Emacs + a better language + a better/bigger ecosystem... Because while lots of people use ELisp in Emacs, more people are just calling use-package on what ever package someone else created.

Take another example, JavaScript. You want to write a dynamic web application, you use JavaScript. There is no shortage of tweets of JavaScript trivia where the person shows JavaScript adding two non nonsensical objects together and getting an even more nonsensical answer. If you don't program in JavaScript (or even if you do) you look on in horror and go "Why would anyone use this awful language!". Then you go use your electron based desktop apps, and run millions of lines of JavaScript in the browser. Are there better languages for the web than JavaScript? Sure lots of languages clear that low bar. But is there any language with a comparable ecosystem that also works as seamlessly in the domains that JavaScript works in? I'd argue no. JavaScript has so much momentum that it even spills over into areas where it shouldn't be used (I.E the desktop and the backend) but it can go anywhere at this point (including custom ARM CPU instructions https://developer.arm.com/documentation/dui0801/h/A64-Floati...)

I'd say the same thing about Python as I did about JavaScript (I am a Python dev). If the official OpenAI Api had been written in Racket there would be millions of Racket users right now and a bunch of new and awesome package, but it's written in Python.

Another example is Zig. I actually think that Zig has a chance to compete in the programming language. I started using Zig not because of any particular feature of the syntax, or the libraries it had, but simply because trying to compile cross platform C/C++ applications using a combination of GCC, LLVM, MSVC, and building for Arm, X86_64, etc is so awful, that using Zig instead is a better solution. This will be the gateway for most people to Zig IMO, and then from there the ecosystem will follow.

There is one edge case and that is Swift. I actually think Swift is a good language, and has a lot going for it. It definitely has the chops to be a good low level compiled language with good C/C++ integration. But a lot of its popularity is due to Apple having the power to make it the de facto language on iOS, just like Google can with Kotlin. But that will only help on the platforms they own (which are admittedly a lot more than most languages), but to gain the viral cross platform adoption, it will require an actual effort on Apple's part to make that happen, along with some dedicated fans of the language. Right now, using Swift without Xcode is hard, even with the VsCode plugin. I know Miguel de Icaza is at least one of those hardcore Swift fans, and is trying to get the Swift Godot project up. That could be the gateway to Swift for people outside of the Apple ecosystem but we will see.