Sony celebrates 4.2 million PSVRs sold — or about twice as many Sega CD accessories

Earlier this week, Sony celebrated a (somewhat arbitrary) milestone for PSVR: 4.2 million headsets sold. It sure sounds like a lot, but if you put it in comparison to other excessively publicized console accessories, like the Sega CD or the Kinect motion camera for the Xbox 360, it’s a far less impressive achievement, as noted today by Ars Technica.There are two important numbers to look at for the PSVR (or any accessory): how many units it’s sold, and what percentage of total conso