There are lots of channel on which you can gamble online from your smartphone. It is up to you to check whether it is legal in your country or not. You need to read all related documents. In today's time there are many Android and iOS apps which also works in the same way as gambling. These are legalized betting apps.
If you are mature and 18+, then you know the risk of gambling. But for those who are not 18+ it might be harmful. For those I request parents and elders to use phone tracking apps
and keep an eye on those. This way you can check whether these kids are involved in some wrongdoings or not.