My first professional dev job was COBOL and it's associated tech, a majority of the stuff we did was banking stuff and at the time it seemed like that's what a majority of the COBOL market took up but I could be wrong
Ah COBOL, oddly enough I started my first dev job in COBOL in the banking industry(I'm in my 30s and started my professional coding career in my 20s), I have mixed feelings about it...it's a weird language but it has it's place, I wouldn't advise anyone to jump into a COBOL career path unless you are doing it for a job and a job alone.
This looks really awesome I've always been curious of mental models so I just ordered a copy from Amazon. Also Gabriel, kudos to your work and DDG, I'm right near DDG headquarters and it's nice to know things like DDG are being created in my area.