I find it interesting (and slightly depressing), both in this comment and the responses, that everyone still thinks of VR as a "game thing." It has so much potential beyond games, and that is why it will succeed (eventually). It will take more time, but definitely not twenty years.
The reasons it's not taking off (as fast as some overly optimistic people thought) are plenty. Expensive, yes. Takes space in your home, yes (and most people don't have it to spare). Tethered and can trip you, yes. Biggest of all, there's no content that is compelling enough to reach a wide audience. All of these will change, except perhaps for the need for space.