1. It's existed for long enough that we know it won't just go away and break our hearts. (I used VLC to play videos on BeOS back in college in the late 90s.)
2. No matter how many iterations it goes through, it's still intelligible to would-be time travelers from the past. I.e. didn't get caught up in the "must change the UX around for change's sake" epidemic that still seems rampant.
3. It's always had acceptable performance, perhaps owing to being born in a time of no goddamned Electron apps.
4. It's dependable across platforms, even platforms that I'm unfamiliar with or don't like. Need to play a video on Windows? I don't even know what crapware to download, because I download VLC, because I know VLC runs on Windows and will greet me as a familiar friend in this strange and foreign land.
My hat is off to you, VLC!