One of those things that, like a theater room, would probably take up space and not get used much.
Most people when they want to watch something and have the free time to do it flip open their laptops and sit in bed or on the couch. And can you imagine firing up that popcorn machine (and later, cleaning it) just to make yourself a bowl of popcorn?
Some people are collectors of course, or movie fanatics, or have eccentric decorating tastes. I've also seen the weird thing where people get an urge to replicate commercial spaces in their private homes: a facsimile of a local bar in the garage, a movie theater in the basement, I've recently even seen a gas station (complete with working traffic lights) in the car port.
File it under "not how I'd recommend anyone spend their money but to each their own".