There is concern about the two, but different levels of importance placed, I think. The data they hold and risk losing is more important to gamblers than the money the money they have, and then to the casino, I believe it will be that they have more importance to the money than the data of the many gamblers.
Both are very important. If a casino gets hacked for instance and a huge sum of money was stolen, there are 2 things involved. The first is either they continue running but are unable to pay up their customers or the pay up and go bankrupt. Both will tarnish the trust people have for that casino.
It's in few cases you see casinos able to pay up in situations like that and still run normally. Stolen Data is worse though since Even the customers can be targeted too.