What continues to happen is when the next big thing in text editing shows up--Textmate, Sublime, BBEdit, and now VS Code, there are lots of those users who become disillusioned (for all kinds of reasons) and end up on Vim.
I can’t speak for them but I wanted an editor that I wouldn’t outgrow, was extensible and programmable—Vim does not disappoint.
The composability of Vim is its killer feature IMHO regardless of what’s new and shinny.
I see lots of complaints about VSCode being an Electron app and while its performance has improved a great deal over the years, it can bog down with large files, etc.
And even though I’ve been using Vim (now mostly Neovim), for 10+ years, I continue to learn about features that have been around forever but I didn’t need or care about until just recently.
One of the articles that got me started down this rabbit hole is the famous (in certain circles) "Your problem with Vim is that you don't grok vi.” essay that’s a response to a question on Stack Overflow [1].
[1]: https://gist.github.com/nifl/1178878