That's quite alarming. Do you have a data or link to support your statement? Teenagers should be guided to keep them away from vices including gambling. If that's noticeable enough in your country. your government should do something about it.
Teenagers who do gambling are worst than the adult gambling addict, because the fact that these children doesn't have any source of income yet but only through the allowance they get from their parents, will make them think it would be fine to steal money from their parents or worst from their friends and other people.
I don't see "many" teenagers who got addicted with gambling though, at least in the places I knew including here in my country. Most of the teens are either doing sports, night life, and even drugs, but not much in gambling. If it's really happening in your place where a lot of teenagers who are addicted with gambling, I'd tell you that's really alarming.
Indeed, each country has its own differences, including in terms of gambling. In my village or area there are lots of teenagers who gamble, for example at a wedding there will definitely be gambling there, there are adult groups, youth groups, and this already exists and is definitely done, maybe this has something to do with tradition. Even with small stakes, teenagers and adults gamble in the same room. that's what happened in my area. This may be very worrying in the future, because teenagers can become addicted and this is difficult to stop.