There is one fairly simple reason: It is way to expensive. Especially in the EU.
Just as some example: The HTC Vive Pro Starter kit (not even the full) sits at a whopping 1199€ (1359,28 USD) in the EU and "just" 968,53€ (1098 USD) in the US. Both prices are way too high, preventing the tech to actually settle with the non-fanboy user. And i do mean fanboy here! Most people on the internet "defending" the high price simply say "just save up some money and you will be fine.". Thing is: At theese prices, people buy cars. There is simply no way the average consumer, only slowly even being able to afford a computer beefy enough to even run VR (especially with the alltime high of graphics cars prices) will not throw out a top-tier graphics card (at time of writing, RTC 2080ti sits at 1100€ in the EU) for "just" some piece of tech he barely ever will use.
And here is the problem: VR is "just" a piece of input-device bundled with a special gimmick, Virtual Reality. Now, people defending VR may say "it is not ment for everyone" but this is the thing they fail to realize. With VR not being for everyone, VR will fail. The entry barrier (the beefy PC) already is high enough that most people out there simply cannot overcome it. But even if the entry barrier is conquered, there now is the problem of the absurd price point.
Now, smart users may point out that there is an alternative, the non-pro HTC Vive. And you are correct, kind of... See, the first generation VR can hardly be sold to anybody who wants to play games casually. It is not comfortable (like most Gen1 VR headsets), has a horrible resolution causing SDE and reading text with it is a nightmare kind of.
All this, makes those headsets suited for enthusiasts, but not the average John Doe who just wants to enjoy playing some games in VR.
This is where Gen2 VR failed miserable: The Price should have gone DOWN and the SDE should have been mostly eliminated. Thing is, price doubled. That is bad. It is literally as simple as this.
Want VR to succeed? Put the headsets into a more "sweetspot" like thing, that does not requires people to save their earnings of a whole decade on theese things.
Want VR to fail? Then leave the price way too high, making the headset itself as expensive as the computer you just purchased to use one of those.