Earlier quoted context omitted.
Every time I'm sysadminning some Linux server or another. It's everywhere and does the job well enough without me having to learn vim :-D I also often use it to look inside random files on my Mac that won't open anywhere else (e.g. .xml, .json, files without extension names).
I think vi is probably more ubiquitous though, especially since it’s included in busybox which powers almost all imbedded Linux hosts. Still a good idea to learn a little vim
I know how to get out of it, and also how to get into insert mode and make the most elementary of changes. I tried going further but it just doesn't mesh with whatever form of memory I have installed in my brain :-D