Besides, these articles sometimes to have the full story, maybe the man is a religious man and gambling is something that might be frowned upon and was trying to stick to his principles....whatever it is, give it time, the son will explain himself and they will find a way to agree on how to receive the monetary gift.
In this case, reading the whole story, one thing is clearly understood, except for the father, the other members of the boy's family are interested in keeping the money won by the bet. But the boy's father is not agreeing to spend his gambling money for the benefit of the family for some religious reasons. If you look at the boy's older brother's post, they only told the netizens that the gambling money is with his family should be spent. Moreover, the boy's mother is willing to spend the gambling money with the family because the boy's family still owes two months of house rent. If the boy spends the gambling money for family purposes, then his family will have a great life in the future.
Well, the won amount will surely create a big difference in their lives, but knowing his father is a devotee of his religion, then taking money from gambling is a big sin and such instances should never be tolerated. He might be lucky enough to gain such amount but if he will stick to what his father believes, everything will come into waste particularly his efforts put in gambling.
From what I see, if you look at the context in the picture and the OP's explanation, it actually says that the father is a religious devotee, this is speculative because it is not explained in more detail than that, but there are indeed several possibilities that the father was indeed like that.
But on the other hand it is also a matter that in my opinion is more of a principle and the father does not want to violate that principle and of course that is his choice.
It will not be in vain because indeed it is also the right of the child, it's just that the father doesn't want to accept the money now it depends on the child what to do with it because he is actually quite an adult in my opinion and even this kind of thing is good in discuss it with your parents but the decision must be based on yourself because already an adult he also knows what is best for him.