Instead of outrightly banning gambling, how about if the concerned countries officially include gambling education in their academic syllabus, just like sex education is taught in schools. Gambling education will teach the young ones the dangers of gambling and promote moderation in gambling. Will this not be a better way to handle the gambling cases?
This varies greatly between countries. In mine, for example (Brazil), sexual education is not even part of the curriculum in schools.
But, regarding the subject you addressed, I think that a specific subject on gambling is unnecessary, however it would be very useful if all schools in the world could teach children basic notions about economics and investment, that would be something very relevant and certainly extremely important for the development of a person and the long-term improvement of the country.
However, in some countries this will be an impossible subject to teach, as teachers are not even paid adequately, so analyze with me... how is a teacher going to teach financial education if he doesn't even know what inflation is, something basic, and is he "drowning" with his own credit card?
The conscious use of money and what can be spent on gambling or any other high-risk business should indeed be fundamental in schools, but for many countries this is unfortunately far from becoming a reality.