You got it from a lucky drop just like me. You didn't "earn" anything. Me and a friend of mine were in crota's end and I got the IB and she didn't. She then bought it from Xur when he came. Technically, she did more than I did for it. The raid, and EARNING those strange coins. It disgusts me that people get so upset when Xur comes. If your one of the people who bought it from Xur for strange coins, then good work. You earned it. If you're someone who got it from a lucky drop like me, then be happy that you had some luck on your side.