Why one earphone?
Unless you're chilling at home, you need to be able to pay attention to your surroundings. This item lets you do that. it leaves one ear open for hearing what's going on around you.
Maybe you have a job where you'd get in trouble for listening to music or the baseball game on the clock? Hide this under your hair or a hat and you're good to go! You can still hear your surroundings while getting yoir chill on.
It has a mic so you can also make and take phone calls on it! While having two headphones for immersive music is best, this unit is better for paying attention to your surroundings.