Those that are emotional and have lesser strength to control themselves and emotions, they're very prone in being a gambling addict.
Or at least we would not expect them to be wise since they have no sense of responsibility and financial management just yet meanwhile adults or at least the functioning ones would know the importance of controlling oneself. It is good for us to sometimes treat ourselves and do something we enjoy but we always go back to being responsible which kids might not want to do ever.
Do you think a 15 year old would care about the consequences of his actions? No because he is not thinking of his future yet but adults are already living the present they need to protect. There are only rare cases where adults are less sensible than kids and might be more vulnerable to falling addicted.