That's a good question, so I'll try my best to answer. Music has always been a very personal thing for me, to the point where the variety of stuff I listen to defines part of my personality. I'm quite an introverted and private person, so playing music that others can hear simply makes me uncomfortable (even if they eventually forget about it in the future). I reserve the stuff I enjoy to those who are closest to me since I'm fine with them seeing a piece of who I am. For me, it's also a nice way of showing my respect and consideration to others.