That wagering rule is for some purpose. If there is no wagering requirement, some people may use the casino for money laundering purposes. They can still use it for that evil purpose but at least they have to fulfill the wagering requirement and risk their money. Additionally, if you can deposit money into the casino and then withdraw it to a different address, many people will use this method as an alternative to a mixer. With a mixer, you have to pay a specific fee but here, you can achieve a little bit of mixing but without any fees