Looks like the father knows the consequences of his son's action and he just wants to guide him no matter what the scenario is, we don't appreciate this kind of love from our parents until they are no longer here with us and by that time we realize that no one has ever been truthful to us except them. He should always listen to his father and learn to be contented in his life since they all have the means to survive. If he accepted it, I'm sure it won't be the last time the son does it and until the whole family is addicted to it.
What we consider good is not necessarily good according to other people and what other people think is good may not necessarily be good according to us too.
We need to know that there are those who think gambling is good and there are also those who think gambling is bad. And there are also those who think that gambling is haram and there are also those who think that gambling is halal.
And perhaps the reason behind the person not wanting to accept the money earned from gambling is because they think that gambling is a bad thing and an act that is haram according to religious law. And I really respect the decision he made, because his fortitude and faith were not shaken just by the amount of money his son gave him, even though he was experiencing financial difficulties. I really respect him, compared to people who keep shouting that gambling is bad and gambling is haram, but when given some money from gambling they immediately fall silent and take the money. LAUGH OUT LOUD...!