the gambler was indeed at fault because he had used money that was not meant for him. but on the other hand the sender also has a little mistake sending large amounts of money but is not careful in writing the address to be sent.
Both of them have the fault. Think both of them that are responsible for their own mistakes.
in the end the gambler also admitted his mistake and intended to return the money he had used to gamble.
so the gambler is not completely wrong
It's still not rare to see people admitting that they're wrong and if it's about to be returned, that's a good call for his actions for being responsible. That won't make him lose something but that will show how he's willing to cooperate because the money wasn't him. Lessons are for both of them and they'll be better and won't do mistakes again that are the same with this incident.