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Gambling is definitely not something which can help you to repay a loan. If someone is stupid to the extent that he/she starts gambling with that goal, I can guarantee that they would not stop until they lose everything, even if they initially won what they needed.
I believe that a gambler that gets too addicted to gambling any circumstances might happen. It still not going to stop until it meets the end or in short, the end wherein you will realize its regrets. Also gambling can't be considered as way to repay loans and debt, it might also be the reason to worsen the deficit, also don't think that even a gambler wins big money will stop playing I guess its mindset will worsen only because he/she will believe that he/she has a lot of money and can't lose that much and eventually without realizing all the money will vanish in instant.
I think it's important to mention that sometimes people win when doing exactly what you described, and namely because of that this problem exists. If people were always losing, gambling wouldn't be around by now. But people should know that there are things you don't gamble with, and an amount of money that is significant for you is one of those things. So, even if you started from a small balance and then won big, stop and think whether you should continue, because maybe now it's an amount that you need for something other than gambling.