Why do we say “break a leg” when wishing luck?

Going to a job interview? Someone tells you “Break a leg” and it means good luck, don’t mess up. What kind of maniacal society do we live in? The expression has an origin which does represent our world violently.

During the World War 1, air combat was one of the most difficult and dangerous aspects of the war. German soldiers wished each other luck by saying “break a neck and a leg” which was often considered a good thing since most of the time the pilots would lose their lives, which was a lot common.  After the war german actors picked up the line, wishing other luck in their jobs. Eventually the expression went to Britain and then America, where it became “break a leg”.