I mean come on, it’s pretty obvious that it’s this Japanese man’s fault for not double checking as to why he was sent the extra money. That’s a whole lot of money being sent to someone by mistake. Not to mention it’s abundantly clear that this guy has major gambling issues. What a fool ! Lol
Receiving such a huge amount of money which is unexpected is too alarming. He should double-check it in the first place or question it but it's his fault for using it to gamble intentionally.
He really meant to spend it and he might actually have an idea that it was sent to him by mistake so he gambled it right away.
I can't think of any possible reasons why he would gamble that large sum of money if he knows that it wasn't his money in the first place, he should contact his bank that the money was mistakenly sent to his account. Maybe if he had done that, he will be lucky enough to receive a reward but unfortunately, he did not so it's safe to say that he had it coming and he would really go to jail for that.