Soooo I thought why not compare this number with other PC VR games on steam and.... wow the most close a steamVR game has come to Alyx is VRChat and that game is FREE on steam with a concurrent player number of 20, 0320 and as for the rest...
Superhot VR: 839
Boneworks: 8, 717
The Elder Scrolls V: Skyrim VR: 3, 048
Beat Saber: 4, 472
so Alyx's 42K concurrent players number at launch easily dwarfs ALL of the PCVR titles released so far on SteamVR.
Hence I'd be totally inclined to believe in what this user is saying...
I think, to put those others in context (and to give HL:Alyx it's props), there's never been a VR title that has had DAY ONE HYPE before really. Everything else has been this constant interest thing that just ticks along getting sales. We know that other VR games, like Beat Saber, have done really well in sales but that's presumably over time, not all on one launch day. It's taken time for the market to open up to VR and since Superhot VR, Skyrim VR, Beat Saber etc launched we've seen tons of new hardware at lower and lower pricepoints (like the Quest!) while those games have continued to be popular. But constant, steady sales over x amount of years/months doesn't equal maxium concurrent players. Half-Life has absolutely had people waiting for launch and then all jumping on at the same time. Worth it too.
Also side note that Superhot, Beat Saber and Boneworks are all available elsewhere other than Steam, like the Oculus Store. SteamVR doesn't equal PCVR. I imagine they've all picked up huge sales and have a lot of their playerbases playing via the Oculus Store, considering how prevalent the Oculus CV1, Quest and S are in the PCVR space.