I guess there's no other option but to move on on your funds lose since as Roobet support they cannot help you in this case since they are not supporting BSC network in their casino.
So with those situation I guess that put a dot on your case and I guess there's no one here could help you to solve that kind of issue.
The amount is question is 3.1 ETH and it is not a small amount. This amount is available on the BSC Chain, so if the support wants they can recover the funds manually. Even in an automated systems, the manual intervention can be done for the interest of the gambler where he deposited on the wrong chain by mistake.
So, the only option now is that a moderator on this forum, who has contacts with higher-level individuals at roobet.com, might be willing to help me resolve this problem for a fee.
Moderator of this forum has no connection with the gambling site owners. Gambling sites just have an ANN thread listed here and that does not mean that the moderator is involved in that business. So no mods or admin of bitcointalk can help you recover funds.