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What I want to know is: Did I do a good job by using gambling to save him? Or do I just make him have an interest in gambling as a source of income?
You did nothing wrong by giving the man money and you did nothing wrong by encouraging him to gamble, after all, it is another chance for him to try his luck, especially when you did not have the excess amount that would feed his family. But you are so wrong not to have further educated him about gambling as an inexperienced gambler, I am sure that this man will come again and that could lead to his ruin over time. Gambling is not a child's play so we should get ready for it both financially, skills-wise and with mental preparedness, but in his case, it's not so.
The easy money he made due to your encouragement would have convinced him that gambling is as easy as that, but he might not admit that luck heard his cries and visited him due to his condition. I wish the man well, but I still task you to locate him to finish the job you've started by educating him appropriately.
Yes of course someone with such an opportunity then getting a win that doubles his money is an incredible stroke of luck after a previous loss.
But I'm also pretty sure the person will be motivated to do it again, because in his mindset, he wants the same win back or get a much bigger win so he will play more aggressively, so for this responsible gambling supervision and training is needed for the person, it's a shame if getting a salary from work is risked to risk everything that could potentially destroy him.