Or, as Cook said himself: "I've been wearing them [AirPods] for a while. And because they don't have wires on them… The wires tend to help the earbud to fall out, because it applies weight on those. By snipping the wires, I have never personally had one [AirPod] fall out."
Eureka! Apple wins again!
Roberts then tested the Airpods out, and seemed pretty confident that they’d stay lodged in her ears, even after vigorous head bobbing: