Most of them are like this because I saw a movie with the same stories where he was shocked when he looked at his account which was almost the same story as the Japanese guy here and he went to gamble and bought everything he wants. Well, it might be just a movie but if you look at it in another way, they just portray what could possibly happen and they nailed it. Anyway, the title of the Movie: War of Money it's a Korean drama and has lots of lessons involving money.
Not familiar with the movie, but yes, it does happen now. The man has a gambling addiction problem because if he does not have,
he will not be tempted to use that huge amount for gambling, he can simply send it back to the bank as knowing the Japanese culture
they are very conservative in terms of trust concerned. Now, the person was convicted, and he needs to pay the amount that he spent
from his gambling activities. He can't escape or make an alibis even it was a honest mistake that huge amount is not entitled to you
you don't have any legal right to use and abused it, especially using it to a vice like gambling.