I work to make money. I then use that money to purchase things that I need or want. Now I could use that money to gamble and try to win things like a raffle or at a casino. If I buy a big screen TV that I saved up for you won't say that I didn't deserve that since I worked for it(you could say that just to be mean but you get the point). There are multiple 3 types of currency in Destiny. Motes of Light and strange coins are earned through events, leveling up past 20, and other various things. Xur gives guardians a chance to buy an exotic with their hard earned currency. Not everybody gets lucky with the RNG system. Xur is Bungie way of giving those unlucky players a way to get their exotic. They still earn them because they put in the time to play and gain the currency. I'm sure their is a post like this but these are my thoughts and I wanted others to hear them!