I just stumbled over this article:
https://venturebeat.com/2019/03/25/playstation-vr-sales/

Quote: "Sony has sold 4.2 million PlayStation VR headsets

“We’re also very excited to reveal that we have officially sold-through more than 4.2 million PS VR systems worldwide as of March 3, 2019,” PlayStation social-media director Sid Shuman wrote in a blog post. “We’d like to thank our fans for the amazing support for helping us achieve the milestone.”

That sold-through designation is important because it’s not just “shipped.”
Instead, 4.2 million people have actually purchased the device.

This means that PSVR likely still has a lead in the premium VR headset market.
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Looks as if an affordable price, ease of set up and a good catalogue of games, is all that's needed to make VR a success (on Sony's system).

Well, that and a headset that is comfortable to wear.

For a technology that is some what new and being released for sale after three years and only 4.2 million Virtual Reality (VR) head sets being sold in that three years, with not a lot of video games developed to work in Virtual Reality (VR) that give you lots and lots of hours of gameplay time I would not call that success.

A bunch of video games that run on Virtual Reality (VR) head sets take anywhere from three hours to complete to eight hours to complete.

That one Batman video game I can think of was said to be completed in four hours I think?

Interesting, considering how low end the PSVR is in the overall space.

this is only the numbers for PSVR, it does not take in account PC VR headsets. There are much more games and headset for PC than consoles at the moment, so your statement here is not quite attuned to reality. and even if it was, as you say, this is new tech and early adopters are always in low numbers, so it is a success no matter which way you cut it.

The HTC Vive and the HTC Vive Pro combined sold something like only 350,000 head set units.

The Oculus Rift sold something like 200,000+ head set units with all of it's versions combined.

The Google Cardboard I think sold like 2+ million units, but Google Cardboard is not all that good anyways.

As I said a bunch of Virtual Reality (VR) video games take only like three hours to complete, we need more bigger games that have support for Virtual Reality (VR) head sets like The Elder Scrolls V: Skyrim Special Edition does.

sources?