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.
This is really the problem if they commit mistake by sending funds on wrong network since they provably get an issue for recovering it. I guess what need to do is to send again some message and ask for possible solution and he should state that his willing to pay recovery fees which is common on exchange as I remember and maybe this is applicable on casinos to. And maybe they could help if they see the user got an issue like this is willing to cooperate and wait for how long this issue will be solve.
It really awful to encounter this issue that's why its good to do double check before sending funds to other platform so people could avoid this kind of issue.
In principle, the support service of a large well-known casino, such as Roobet.com, for example, of course should take into account that sometimes players who are completely immersed in their game can make mistakes. Here, of course, it is worth considering that a player when he is completely immersed in the game can simply do so through inattention. And to help return such money if it is possible manually, in my opinion, this is the responsibility of the support, if he is really user-friendly to his clients.
Of course, you need to write to the support again and then inform here about their response. After all, the amount is really quite large.