A certain amount of risk is unavoidable. Some risk might even be desireable. But with risk come the responsibility to not injure others.
A pedestrian using headphones should have the courtesy to stay well to the side of the trail.
A cyclist wearing headphones do the same while giving increased attention to intersections and merges with traffic which his/her attenuated hearing might not provide warning.
Just staying on my bike is risk enough for me.–Corrie
The debate over whether it’s OK to ride a bike and listen to music is at least as old as portable headphones. Surely, when some intrepid cyclist first took the opportunity to do both, a bystander was quick to lecture, admonishing him to remove the headphones and, while he was at it, to put on a helmet and eat his vegetables.