Looking for a nice, solid, well-documented library to do something is difficult for most stuff. There are some real gems out there, but usually you end up having to roll your own thing. And Lisp generally encourages rolling your own thing.
Is it about intelligence or just not being used to/having time for learning a different paradigm?
I personally have used LISP a lot. It was a little rough at first, but I got it. Despite having used a lot of languages, it felt like learning programming again.
I don't think there's something special about me that allowed me to grok it. And if that were the case, that's a horrible quality in a language. They're not supposed to be difficult to use.
I think it allows very clever stuff, which I don't think is done routinely, but that's what gets talked about. I try to write clean functional style code in other languages which in my book means separation of things that have side effects and things that don't. I don't think I'll have difficulty writing standard stuff in Lisp with that approach.
Just because it allows intricate wizardry doesn't mean it is inherently hard to get/use. I think the bigger issue would be ecosystem and shortage of talent pool.
JavaScript and Python have adopted almost every feature that differentiated Lisp from other languages. So in comparison Lisp is just more academic, esoteric, and advanced.
This is only true if you define "Lisp" as the common subset. If you look specifically at Common Lisp, neither Python nor JS come close in terms of raw power.
It's pretty rare because when it was being originally designed the main intended use case was for bragging about the cool unique niche programming language you use on your blog posts. While it's a very good language for being able to recursively get itself onto the front page, it's not so good at conformist normie use cases.