Prolog is strange. On the one hand it makes sense. On the other hand it seems to just be not a very practical language. People don't seem to stay with Prolog whereas they stay, say, in python.
Prolog is a very practical language for particular tasks. Languages are tools that fill different niches.
Besides, people do stay with Prolog. The language has been going strong for many decades. New Prolog projects pop up often. This can't be said for many other unusual languages, which perished in academic obscurity.
