Earlier quoted context omitted.
Out of curiosity, what is it about an IDE that you find useful...? I'm probably just a heathen, but I've always done the build/run steps on the command line, and Sublime has LSP for all the syntax & semantics goodies other than that -- like for Python, I've got Ruff (syntax), Jedi (semantics), and CoPilot (autocomplete) running happily, with what I feel is an impressive amount of configurability. Are people just work…
Some of us have jobs and do this professionally, not as a hobby. That’s why we use an IDE. Vim is a fun toy where you can hack together a poor man’s IDE but I grew out of that phase a long time ago. In some cases we are forced to use a specific IDE. Not optional.
I have a normal job using go + angular/react, lots of databases (postgres) and lots of bare-metal OS shenanigans. I use Vim with 2 plugins. One fuzzy file finder and one for integrating with go.
I've used the JetBrains products daily for many years. These are very slick and I basically regard them as works of art, but I ultimately don't need them (anymore?).
It took many years to get the vim movements into the core of my being and this was indeed quite an investment, but my hands usually move the code now. Sometimes I can just watch them shifting blocks around as I'm barely conscious anymore of the actual physical movements themselves. This sounds like satire I'm sure, but I'm dead serious. This is actually a thing that exists. Not fundamentally different from being unconscious of the key presses when touch typing.
Once you get to this level of familiarity with vim, the shell and the entire Linux or BSD ecosystem things really start to fly and the need for an IDE quickly fades into the background. It is at that point that "why do you need an IDE?" because a serious question.
(Of course this is all moot if you are embedded in a highly specialized ecosystem with its own tools and ways of doing things.)