[didibus]

It's interesting too that of the top 5, only Go is a non-functional language, the others all are: Clojure, F#, Scala, Elixir.

Right now my guess is that, if you also look at one of the other questions, it turns out Clojure has one of the highest ratio of senior to junior, like Clojure devs average a higher amount of experience as well. I haven't checked the others like F#, but my guess is that most dev using functional programming languages actively and professionally tend to be more senior and thus command a higher salary mostly. That means there isn't as many junior or mid-levels to skew the average salary down, where as my guess is other languages might have an even bigger number of new devs using them like JavaScript for example, which would skew the salary average towards their pay levels.