Your post made me think that that bank did not care much about that person and personnel in general. Few fails at work, caught gambling - got fired. In someway I think it might be more human to try to help that employee with his gambling. I dont think that bank fired him immediately when they saw him gambling for first time. I think there were talks, warnings before firing that person. If they see a person has problem, it would be best to help him. Instead, now he still had this gambling problem, and now he is jobless in addition. Bank made his situation from bad to worse.
So exactly was the bank supposed to do according to you? They are are financial institution, not a facility for recovering gambling addicts nor a mental institution. It is sad, but that is how most societies around the world work.
If I was found gambling at a job here in my country, when money which is preperty of the company, they would have no compassion for me whatsoever and they would fire me immediately, that is the natural reaction for any company which in their business to make money, not to lose it due to the bad habits and problems of their personnel.
After getting fired, that person is supposed to take those consequences of their actions as a wake up call, in order for them to change their way of living and control their problem gambling,.it is on their own hands and not in the control of the bank, which only sees for the well-being of the business and their investments.