VR tech still isn't ready for truly mass adoption, but there's definitely cool stuff in there. It's just not for everyone. I think it'll get there eventually, but it's gonna take a long time.
> What is the "killer app" that people see here?
For some people (myself included), it's Beat Saber. Super fun rhythm game that wouldn't work outside of VR. Very useful for exercise.
In fact, VR is good for exercise in general. There's a lot of rhythm/fitness/sports games, or ones that aren't explicitly targeted at that area but still give you a workout, like Gorilla Tag. Having a big library of games-that-are-also-exercise that you can use at home is a big benefit. If you're the kind of person who likes games, this is probably a more effective use of your money than, say, a treadmill.
Of course, some people like various VR games for their own sake. Playing something like Blade & Sorcery or Dungeons of Eternity is certainly much more immersive than regular video games. I felt like a murderous sociopath when I first played B&S, and the graphics aren't even that good!
There's also people who want to use VR for productivity purposes, like having infinite screens, though I think for most people the comfort level isn't there yet.
And lastly, porn. Of course there's VR porn.