He enjoyed using the money disregarding what will be the consequences of it. That guy should learn his lesson.
Indeed. Its a huge amount accidentally sent to his bank account, he's aware its not his money but still use it to gamble as if its his own. Instead of coordinating to the bank he gambled it away.
Now, even he return the money, it doesnt mean he's a good guy. Its his responsibility and he should face the consequence of his action.
He must have been careful, As he is not the owner of this assets. This money should never be spent on gambling. It certainly proves that the man did these things only for his personal interest so he was a fraud, He didn't control his greediness.