Typical gambling rule: You bet some amount of money. If win - get double the bet (some cases can be more or less). If you lose - you lose your bet.
ROM gambling rule: You bet (buy) some "chance" jewel items from IS. If you have success (win), you got for what you paid. If you lose - you lose your bet (money) twice !!! You lose your bet (money) for the purchase + you lose again becasue item level dropped.
Or lets say: you have one floor house, then you find contractor and pay him to build 2nd floor. Week later contractor come and say: Sorry, you dont have a house anymore because we didnt manage to build 2nd floor and we destroy first floor. If you want to build 2nd floor, you have to pay us first to build first one again ...
Can you see the scam?