The only exotics one can earn are from exotic bounties. Getting exotics from engrams, night falls, crucible are luck. What 2 kills going -20 let's give you a suros lol. It's all based off luck. Everything you buy from xur is earned. You do the weeklies to get guaranteed strange coins which you save up to buy from xur. I know someone who has passed the hard raid more than 15 times and has only gotten the corrective measure from it. There's many bad kids who push off Atheon and get the vex lol. All this earning stuff should stop. Most of it is luck.