I have a home theater. I don't know how big the market is, but you can buy receivers from a half dozen manufacturers (Denon, Yamaha, Sony, Onkyo as well as a bunch of speciality brands), digital projectors (Epson, Sony, JVC, BenQ and also a bunch of speciality brands), and all manner of ancillary items (sound proofing, audio treatments, theater seating, etc).
/r/hometheater/ has nearly a million members.
https://www.avsforum.com/ is pretty active.
TVs are still getting larger and they've recently crossed the 100" in size.
So yeah, there's a least a few dozen of us!