I think 18 plus persons are suitable for gambling, because boys and girls under 18 will be studying at that time. If gambling is indulged in at that time, it is certainly fatal to the society, and a threat to the family. Because a gambler can never do anything good, he will always be addicted to winning, and he can do various evil things to earn this money by gambling.
Well the reason why 18 is the number is because this is the age one is considered to be an adult legally and can enter into contracts without claiming to be a minor!!
So anything below this age should tell you the person is still a baby under the supervision of a parent or guardian, simple as that!!!
But I would suggest this age is raised to 21 to allow users to make informed decisions unlike when the mind is still fragile.
But who has set that at 18 person turns from teenager to adult? There is strange cycle of things. For majority, gambling is about money (only few do it really for fun). About spending and earning money. What, a person who is younger than 18 isnt allowed to operate with money? Teenagers work from 16, get money from relatives even earlier and go shopping. Moreover, they drive cars and become parents when they arent 18 yet. Dont you find it strange?
Well I think this adulthood stuff or when a person is considered to be an adult is highly dependent on cultural specific concepts.
You wouldn't be wrong for pointing out how strange it is that people under 18 are prohibited from gambling because they are assumed to be minors, while in some countries, they're already old enough to handle their own finances and already working for their own money, but we must also consider the majority view, even in those places where those below 18 are already working, not all of them, in fact, majority them cannot really manage their emotions very well, especially when it involves losing money, it'll be very easier for them to get addicted faster, than a person who has come of age and has more responsibilities.
Yes it's not always about age, but age comes with experiences, experiences in various areas of life, and these experiences are mostly what helps you to make some calculated decisions that would've ordinarily put you in jeopardy if you hadn't done it right.