It seems to me that if your money really has been sitting idle on your account in the BSC network for so many years, and the account is really controlled by this casino itself (specific casino employees have the keys to it), then it is not entirely clear why this money has not yet been returned to you manually. This is simply checked.
However, it is possible that the automation of payments and security rules simply do not allow using the manual mode in this case.
By the way, I would really like to know this from those forum users who have encountered a similar situation.
I don't know Roobet team have process to support users for recovering fund like this. On centralized exchanges, some can support you but they will charge you not cheap support fee in such cases.
I see the fund in this case is not small and the user can afford to pay support fee if Roobet team requires it for fund recovery. The bottom line is there are many other things to consider on Roobet side that can make them want to support or don't want to support the user. If in ToS and Help page, they have no mention about fund recovery, the user will only have a last hope, contact support for escalating investigation and support.