When a thing turns habitual surely it'll kill time. One such thing had taken place with employee. It is not about gambling, as said whatever he had done apart from his assigned task during the work hours is going to stop his productivity as well as the progress of the firm. This is well understood by the Boss and he had fired the employee.
I said before that this mistake was not caused by gambling but by an employer's playing at the wrong time. The company should have a department that supervises workers and nurtures them if there are problems like this happen again, don't get fired right away before the issue is clear so that the situation can not make a one-sided disadvantage. A problem like this will occur happen on the next time if the company doesn't have a specific rule on how to work in that office because gambling sites around the world have been played very often by workers during working hours.
We don't know if this organisation already have it rule but the gambler didn't stick to it. Even without rules when it comes to our various works, especially when we work under people we need to give every attention to focus on work because I don't think any employer will tolerate any of their workers doing somethings else that is inform of distraction.
An organisation that is handling money like the bank , i don't think they will be satisfied if they found out any of their workers will be gambling during the time of work. Gambling may even be a threat to the manager, especially if the manager is not a gambler, he will definitely have a different meaning to gamble because the way non gamblers sees gambling is different from the way we gambler sees it.