The greatest fear of this action is, "what if this girl becomes addicted? " Just what if? Then it's going to become a big problem for the girl in the future which she might exhibit some addictive behaviors that no man would want to risk getting married to an addict or even after the is married, what happens when she starts using her kids money to fulfill her gambling needs, that means her children will suffer it too. If you must let your kid gamble, it should be at the right age and also with a strict guidelines of not becoming addicted.
It doesn't matter whether it's a girl or a boy, because a child's psyche is less stress-resistant, so I would be against my child getting carried away with gambling. My condition would be that you can only play after you reach adulthood, when you can earn money yourself and play with your own money.
Then it seems to me that the responsibility will be completely different, but while the child receives pocket money from me, I set the rules, and I will do this not for the sake of my whims, but in order to protect my child from unnecessary stress.