Hardly surprising that the "tethered" headsets (I don't think the tether plays any role btw) which are a) obscenely expensive for the non-essential device they are, b) require even more obscenely expensive hardware to support them appropriately, c) are either owned by the poxy bastards from Facebook and d) are largely tied into the poxy shit peddled by Steam or e) require a game console to use that many people don't already have are not quite flying off the shelves.
Meanwhile cheap-and-cheerful lenses-in-a-box can show you anything you can install on your Android phone (including streaming semi-fake* 3D directly from you PC wirelessly) where those interested can later seamlessly transition to an (also Android running, natch) "standalone" headset if they feel it offers anything extra (or just want the use of their phone back...). Sherlock icon for "no shit".
* it is semi-fake** because it's usually two copies of the same 2D image individually re-shaded (based on access to the game's z-buffer) into appropriately squished and stretched simulacra of what you're supposed to see - needless to say, neither eye actually gets any extra information normally present in actual true 3D related to one eye seeing things occluded by an obstacle for the other eye. All this applies only to stuff on your PC that doesn't natively support side-by-side 3D of course - anything that does (including pretty much everything on Android) lets you see proper 3D even on your Cardboard-equivalent. Yeah, the field of vision can't compare to an Oculus - who cares? The lenses-in-a-box are like $10...!
** there's a "full" fake version where the streaming software just duplicates the exact same image for both your eyes (usually if re-shading fails) - it has zero 3D but it's still interactive VR, as in you move your head and the image reacts accordingly because it's still streaming your phone's gyro data back to your PC as mouse movements...