I’m not sure about that. There are at least 120,000,000 steam users, “just under” 2% are active vr users, that’s 2.4 million vr users.
Msfs had sold over 2 million by xmas 2020 (couldn’t find stats newer than that (didn’t look too hard)), assuming 2% are vr users that’s 40,000. But i reckon its far more than 2 million sold now and with msfs i suspect its higher than 2% vr user base as flight sims and vr go together really well.