Steam announced a record 125 million registered users. Of those users, Steam metrics show VR users comprise 1.1% of all steam account holders (1.375 million). While this number may seem small on the surface, the reality is much bigger. It shows Steam VR users more than doubled from last year despite the fact that the two largest VR HMD sellers, Oculus and PSVR, don't use steam as their primary Libraries (PSVR doesn't even have access to Steam). It also doesn't take into account that both Oculus and Valve sold out all Quest, Rift S and Index HMDs, pushing remaining orders from December out until Feb/March of 2020.
It will be interesting what the numbers look like mid year after the influx of AAA titles, scheduled for release in the first two quarters of 2020, are released.