Maybe just because binance is the largest exchange in the world in terms of daily trading volume of cryptocurrencies and its both licensed and regulated in many countries worldwide while roobet is a fairly new, fairly not so popular, shady licensed casino ?
I wouldn't call Roobet a new, not so popular and shady casino. There are online since 2 years, have grown massively and until now, there were not a lot of problems or complaints and everybody gets paid. It is simple, if you don't want to submit your KYC information to Roobet, than you are free to use one of the other casinos but there is no risk to submit your information to Roobet.