Yes, but unfortunately the person did not have the understanding that you mean, so instead of cashing out and enjoying it, what happened was that he continued and eventually lost all the total amount that he had previously won. And this is someone who is included in the people who are too greedy and do not realize the risks that lurk.
On the other hand, I am also quite curious about whether it was a new person who came to the store or a gambler who had subscribed or had often bet there, but at first glance I think he might be a new person who came there, because if he was a regular customer then he should not have run away, at least he said something to the cashier like he owed money and came back again someday to pay it because most likely the cashier must have recognized him. Regardless of whatever it is, I think in the end this is a valuable lesson for the cashier to be more vigilant and careful, and of course this is also a lesson for the store itself to improve security.
Cashier is lacking wiseness because I can't see a place where someone would come to gamble and not paying the cashier instead she regularly keep betting on debt while the gambler believe luck would shine and when he noticed that his luck doesn't come as expected he ran away without even paying any to the cashier leaving her devastated. Usually this offense could lead to her being sacked from that local gambling shop.
Although the betting shop has a poor level of security, such as one of them does not have CCTV at all to at least be used as something to find out about the appearance or characteristics of the person, but in my opinion the incident could have been thwarted or less likely to happen if the cashier really put high alertness and caution by asking the gambler for money every time he wanted to start the game.
So I think the core of the problem is because the cashier is too careless in terms of trusting others, that is a big mistake because we never know whether other people have bad intentions or not, remember that crime does not always happen because of intent but because of opportunity, and yes in the end maybe as you said that most likely the cashier will be fired from his job.
It's just simple stupidity to allow someone to continue betting on credit without payment because I can't seem to rap my around the logic of allow the gambler continue playing except maybe the cashier also is a gambler and believe luck will maybe reach the gambler and then he would pay off but unknowingly to him that sometimes gambling can be really messed up and you can continue chasing your loses till God knows when and still you won't get that amount you are looking for.