If you're trying to judge the size of the market in absolute numbers, you also have to account for the fact that this survey only measures _Steam_ users. So Rift users who don't use Steam, and owners of non-PC VR headsets like PSVR aren't included.

YMMV. My Vive-equipped PC launches Steam on boot, because that lets it install updates quietly in the background as they come in. Otherwise, the first thing likely to happen when I try to launch something is a long wait for stuff to download.

The Vive on the other hand is only plugged in when I actually use it. It gets hot, and I don't particularly want it to burn electricity for no better purpose than to die a premature death.

So even as an active VR user, my Vive is only visible to Steam for a minor fraction of the time my PC is logged on.