The hearables market goes back to the first Bluetooth headsets which were launched in 2001, followed by wireless stereo headphones, which arrived a few years later. Neither made great waves in the market – headsets were associated with cabbies rather than celebrities and Bluetooth stereo headphones took almost a decade to attain any market share. In 2013, that started to change. Major brands were taken by surprise as consumers started to purchase wireless headphones. The most credible reason I’ve heard for the change is that it was driven by the growth of mobile video on larger handsets, with users preferring to dispense with the annoyance of cables when holding the phone screen horizontally. That’s supported by research from Parks Associates showing the average US smartphone user stream music or video for 90 minutes each day. Whatever the reason for the sudden popularity, there is no question that they are now fashionable.

From the article "The Market For Hearable Devices 2016-2020 – And Then There Were Airpods…" by Nick Hunn.