[greaseball]

This sounds like the most likely explanation to me. The only programmers I've personally worked with that wrote code in a functional language for their day jobs were data engineers using Scala for an Apache Spark data pipeline. They weren't paid well because they wrote functionally, they just filled more of a niche role with a higher barrier of entry than a typical web developer.

[kod]

I've been doing Scala professionally for a decade (so definitely not limited to Spark). There was a clear correlation between Scala jobs being higher paying and more interesting than what I was doing previously.