Predictions

The iPad is actually a fairly good example. People have predicted that a tablet form-factor would one day be a popular form factor. Sci Fi has had it for ages -- the Star Trek PADD, or similar. And there were other tablets out there doing reasonably well. If you include e-readers, tablets might even sell in a volume that would chart well against phones or laptops. The iPad annual sales are something like 50M, which is nothing to sneeze at.

If you look at the sum total of the VR headset market over time, you'd probably be lucky to be close to 50M units. https://www.neogaf.com/threads/the-current-list-of-best-selling-vr-headsets-of-all-time-thread-updated.1653893/

But very few VR users are regular users. They are a novelty purchase, like 3D televisions. Apple is late to the show here, and priced way too high.

But maybe I'm wrong. Which is sort of the point of this community :)