Should developing a programming language be a full time job?

I've excitedly following the development of the Gleam programming language. The creator has recently switch to part time employment, to work on Gleam the rest of the time.

https://twitter.com/louispilfold/status/1547981946721951744

The language aims to be simple. Could there ever be a language is simple enough to get moderate adoption, without being anyone's full time job.