That's a sign of irresponsibility, and that person can be a threat to the company, for example if I happen to have a company where we have everything to do with accounting, if I noticed that one of my employees is into gambling he will probably take some stupid risks in the future using money from the company, there are many cases of frauds like this from workers around the world.
I will surely sack him, even if you have a gambling addiction you should avoid gambling at work, you don't know who is watching, go home and fall into your addiction again, not at the office, you are risking your job it seems.
I believe this employee wasn’t fired because he was only gambling, I believe the main reason why he was fired was because he was playing CRYPTO GAMES, we all know by now how much Banks, Financial institutions and even the governments despise anything that has to do with CRYPTO, it’s like a major competition for them because crypto goes against the major thing they stand for, which is Centralization and so banks would expect some loyalty from their employees, so seeing one their workers indulging in crypto games simply means the person is a supporter of crypto, which also means he’s for them and at the same time against them. I believe that’s why he got fired, not just because he’s gambling.