I'm sure there'll be some who replace their monitors with something like this, I'm just not sure how practical it actually is.
For gaming, the question is 'is it comfortable enough to wear occasionally for a few hours?' Unless you're a really heavy gamer, I'd imagine that's somewhere between 1-5 hours per session. If you don't feel like wearing it, you just don't play.
For work, it's 'is it comfortable enough to wear every day for 6-9 hours,' particularly if you can't afford or don't want to pay a lot of money for this and for monitors. I'm not sure I'd really want to go down that route tbh.
That's fair, but personally I wouldn't be prepared to pay what they're asking for this.