At the time of writing (the quietest period in the week for online gaming worldwide), it is currently 54th place in terms of people playing on steam right now.
None of the 53 games above it require/recommend a dedicated peripheral to play.
VR won't hit 1 million simultaneous users in anything until VR displays can render high quality text on a quad (think a screen or piece of paper) and/or provide haptic feedback.
VR is still held back by today's technology for the most interesting uses, but is still acceptable enough for a social space to thrive.
It’s all early days but I think OP is very correct. 20k is comparatively impressive but absolutely shows how limited in scope a “runaway” success looks like. Think of it this way. Traditional console/PC games every year have several AAA titles that sell millions of copies each and have millions of people playing online. Compared with VR where Beat Saber is basically the #1 game for several years. That’s a massive marketplace to sell into with a long track record of winning formula (that’s why gameplay and business modes aren’t innovated on too much). That kind of stuff hasn’t happened for VR yet. Note that I’m not saying it won’t.
Also I wouldn’t look at Steam numbers here - Quest, which is the number 1 VR headset in the world, doesn’t make its analytics visible there [1]. VRChat is top 10 but Beat Saber is more popular I think. So the conclusion is that VRChat is the #1 VR game for PCVR which is a comparatively stagnant market and doesn’t speak to the broader ecosystem.
[1] https://www.oculus.com/experiences/quest/section/31585546237...
To be indistinguishable, though, not quite there yet. Then again, the valve index is still visually nearly, if not the, top of the line, and 3 years old, and it sounds like valve, meta, apple, and some more smaller players are still working on a true next gen, where "gen" is something that feels wholly, indisputably superior to previous offerings. Vive is also still trying but also not doing anything revolutionary. We are however simultaneously on the brink of consumer-level extremely high fidelity, high speed, cable-matching wireless video, and being able to strap sufficient computer power into the headset itself, and no-extra-equipment, compromise-free tracking. VR is absolutely a guaranteed long term growth market