First of all you must understand, that WE ARE ALL part of this. You, me - everybody in this damned game, even if you only sold/bought A SINGLE box. And you shouldn't be shouting at those who abused the glitch, which I'm not even aware of. You would gladly buy the boxes from them to get your beloved sprints and boosters, but all of a sudden you come here and yell at them. Seriously?
All I can think of, that would soften this problem by a bit, is revamping the current lvl up reward system and making it something single individuals might benefit from. Heck, make them unbankable if needed, but I don't want to get the damned lotus leaf hat or first aid pink potions as a lvl up reward -.-
The greatest XXIst century scammer!