Last Christmas and New Year the ideal present, for a girl of a certain age, from Japan to the UK was the neurowear clip-on of floppy ears driven by brain waves to reflect your mood. They would have been played with for one day and then put away forever. Such novelty peaks can be expected with many forms of wearable technology as it enters its manic phase with hugely overpriced acquisitions. Facebook is buying tiny Oculus VR, a Californian company which specialises in virtual reality headware, for around $2 billion. Is it worth that much?