Nah I don't use emacs cos I want lisp. I use it because it was the only thing that made any sense at all on the HP-UX machines I got access to back in 1993. A side effect of that is that emacs does everything I need (with a little bit of pandoc on the side), and I haven't had to learn anything new since.
> A side effect of that is that emacs does everything I need
I'm certain you're telling the truth. And I'm sure that's the case for a lot of old-timers emacs users. But I have the feeling it's less and less true.
People that have used emacs for a long time don't need anything else, so they don't want any change.
People for whom emacs doesn't cover everything want change, but clash against the first group of people (who have been there/contributed for longer), and in the end migrate somewhere else.
I slowly moved everything I need into emacs. That's not because it's superior in all places. It's just that it's the same interface, all the time for me. So I don't have to learn a new editor every now and then.
But my way of working is : many little projects in various languages, much text reports with Latex/markdown, lots of notes (orgmode), bit of email, bit of IRC. In a traditional business, I'd had to use beefier IDE such as IntelliJ (hat beats emacs without a doubt) and maybe Word. But for the rest, emacs fills all the little holes...
One area where I find emacs lacking is appointment (org mode is too big for little things such as quick reminders for today's stuff); a good calculator (calc is very clumys if you compare it to SpeedCrunch for example); a good calendar (emacs calendar is a nightmare to use, for exampe why on earth doesn't display what happens in a day below the calendar and instead forces me to hit 'd' which opens a new mostly empty buffer...); a good console on Windows (on Linux vterm is mostly perfect). Email support is OK with Wanderlust but a nightmare to set up.
Also, since it's very old, there's this warm comforting feeling that will last forever. And also I'm GPL zealot, which helps too :-)
I've used Emacs for... 10 years now? I didn't customize it for an embarrassing long amount of time, but by now I'm comfortable writing elisp code. It is a game changer.
Given enough time I can make Emacs do pretty much anything. I just don't have that much free time (anymore).