That is also possible, right? But I don't think he forgot the risks entailed with it and now he should be jailed for the money that was spent in gambling activities. He should just ask the bank directly about the money that was mistakenly sent to his account rather than just throwing his life because of what the did. It's also unfortunate for that bank teller who made the mistake and I believe he/she was already jobless now.
I'm sure he knows that risk and due to his gambling problem he take that risk and gamble all the money till he losses everything,
In terms of the teller, Not sure if he/she should be sanctions since he just processing the transfer and it's the senders mistake
both sides are the liable with this and not the bank, my personal take though. Bank serves as medium for transaction and
tellers are just processing the request between sender and receiver.