Vim is a text editor that works in a command line and therefore doesn't require a graphical interface or windowing system, or anything like a mouse or trackpad or touch interface. It has a whole system of using the keyboard to do a bunch of things really efficiently, but the user has to actively go and learn those keyboard shortcuts, and almost an entire language of how to move the cursor around and edit stuff. It's great once you learn it, so it creates a certain type of evangelist who tries to spread the word.

This meme template is perfect, because the vim user really did learn a bunch of stuff, and then wants to try to convince other people to do the same, using a pretty unpersuasive rationale (not using a mouse while programming).