I love Lisp (particularly Scheme), and heard that Janet was strongly inspired by Lisp and is "really Lisp underneath", but is really fast and strong at math, so I thought I'd give it a try, and after learning it I started wondering to myself, "why am I not simply using Lisp?"
Though arguably lispy, Janet just wasn't lispy enough for me. It was missing the simple, elegant sexp syntax I dearly loved, and I started to wonder what huge win I was getting from using it instead of just using Lisp or Scheme? Having not found a good answer, I did just that.
That was the last time I bothered trying to learn a "Lisp-like" language that wasn't actually a Lisp, and decided to just stick to Lisp/Scheme. They do everything I need, are good at math, and are plenty fast enough for me.