There aren't enough exotic guns in game to justify selling some 2-3 times over and not having sold others at all. Especially when he will never sell exotic bounty guns or ps exclusives. There aren't as many sellable guns as there have been weeks that xur has been there, and yet he still hasn't sold some guns.
I have ran rocks every week earning 300 marks, that's a lot of strikes each week, at least 10-12 per toon x 3= 30-36 roc or tiger strikes per week, maybe more some earlier weeks, I can honestly say I have never got an exotic drop in one of them, maybe you should think from other players prospective who have been held hostage by the broken rng, we play games to get what we want out of them, it's not too much to ask ffs
I'm in the same boat...no luck with getting decent guns which makes me useless on 30+ strikes/raids. And all I see is everyone else getting rewarded just to rub it in lol. It's getting to the point where I cba with it all :/