The point is that "well 3DTV and 4KTV had lots of backing too!" is a disingenuous argument. It's superficial and shows little more than a surface glance at what's going on.
3DTV was a top down push - big studios saying "It'll be the best thing ever!" There are no indie 3DTV films, 3DTV didn't permeate several types of businesses. It was one enterprise hyping something up to be more than it was.
VR is nothing like that. It's been a bottoms up campaign from the beginning. It's not one industry aligning to VR, it's multiple, on a scale rarely seen. When several sectors of enterprise start to embrace a technology, it becomes transformative. The first step in any world-changing technology's distribution curve is a healthy Demo Scene developing around the technology. VR has that in spades.
Look at all the very big, life-changing technologies. They all gained significant footholds in private sectors, then were slowly introduced to the public, before they became mainstream successes. For decades, you saw computers in offices, in hospitals, etc before you saw them at home. Look at touch screens - for many people, the first touch screen they used wasn't on their phone, it was at their bank, or at a mall kiosk, or whatever. I remember going to a local community college to use their T1 internet line to download shit off of napster waaaaay before broadband became a force at home.
VR will be disseminated to the public the same way. They will be introduced to it in movie theaters, they will become familiar with it at their doctor's office. They'll see it on the sideline of NFL games. Then it'll become normalized, then it'll be everywhere, then it'll be a staple in the home.
People also don't realize that "gamedev" doesn't necessarily mean home consumer use. It also means military.