I have used MUMPS and derivatives for most of 35 years. Although my first company produced library information systems, most of the rest of my employers have used it for medical information systems, and for me that was mostly laboratory information systems. I knew one guy who ran a multi-user system for accounting off of a PC-AT!.
Spent 4 years using Fortran on a similar application. I sure missed MUMPS when having to compile programs and having errors caused by moving too many spaces into a variable!
I've also dinked around with Forth and Icon/Unicon, which I used to create small programs, one which created Valentine bingo cards and another which I used to transform COBOL screen descriptions from mainframe COBOL to a version which ran on PC's.
Sometimes I do wish for a change, but overall I've enjoyed my career.
Perhaps someone in the future will feel sorry for those who now work with C++/C#/Python/Ruby/etc.
It's provided for me for a long time. Can't complain. And provided me a way to solve problems and get paid for it.