People find solace and piece in many ways, many joggers will listen to music as they jog, others whistle while they walk, whatever floats your boat, but I must admit it can be annoying when loud music is thrust upon your ears, I remember back when Walkmans were in vogue, everyone had them turned right up so everyone could hear the music even if they didn't want too, now its the same with phones, very obtrusive.
But people wearing earpieces totally oblivious to their surroundings, traffic, and all can be quite dangerous too.