I would suggest there is one main caveat to the comparison with those figures - all the devices you list were standalone devices.
The CV1 and Vive will not be and are dependent on the buyer already having a PC of a certain spec, or being prepared to buy one in addition which I believe will cause the sales to be lower than those projections.
Well, you are obviously correct, but it still has no influence on the numbers. That is like saying that BMW is only targeting people with drivers license and therefore can´t be compared to a bike.
As of 2014 there were way over 3 Billion with a "B" internet users. Even if we assume that a third of those was already surfing on mobile and pads, that still leaves a market size of over 2 billion pc users.
In any case, this is not about hitting the numbers on the head anyway. This is about demonstrating that VR in general might be a lot bigger than previously thought.
Over 1 million pre-orders for VR in general until the end of 2015.
Total VR units sold in 2016 alone: over 25 million units, with a further growth in 2017 when 2nd gen hardware hits the stores.