Even if no money changes hands, the action is still a substitution of addictions.
The thrill of playing in hopes of the emotional high that comes from winning or the emtional low that comes from a loss is where the addiction takes it's hold.
Add money and it becomes a higher higher and a lower low. Add money and it becomes a nightmare for all around...same as a coke habit or any other addiction. Empty bank accounts, lies, stealing, manipulation... Same list, different drug.
The codie in me would intervene and call management to ask them about such practices being allowed.
Not sure if flagging them to such is right or not but it could be something they are overlooking or need to be held accountable for. (management not the addicts) A socially acceptable addiction is not a suitable replacement and more so when such a replacement distroys lives as much as any drug or alcohol can.