Well when one is single freedom is something absolute, things are always focused on the self and enjoying, it's not bad, but saving is simply very necessary because it is the way that one is going to forge one's future, and when one gets married things will be different if one wants to bring children into the world and have a family, because one will have the ideal to buy a house, a car, give them quality of life, that is what is sought for those who have that dream, those who don't, well, they should also save so that in the best way they have their house and all its comforts, that is what is sought.
It will be no problem if he is single so he can use his money for anything he wants including gambling. But still, he needs to prepare for his future and save his money for half amount and only use the other half amount to fills his needs. He can allocate some money for gambling and be disciplined and not add more money to gambling if he loses that. He needs to stick to his rule so he can prevent more losses. But that will be different if he is already married because he needs more money for his family and if he doesn't prepare from the beginning, he may difficult to fills his family needs. So regarding how much money we are willing for gambling will depend on our finances. If we don't have much money and we don't get a big income, we don't have to try to gamble because that can get us in trouble.