No one can prevent them to engage in technology as the world is already changing to a digital world, but as a parent, we have to be aware of the new technology, adopt with it so we will be able to monitor and prevent our kids in accessing gambling sites or any site that is not yet suitable for their age, with knowledge, you can manage the firewall of your network and block gambling sites, that would easily solve the problem.
Blocking access to gambling sites on your home network will not achieve anything. Tomorrow the child will go out and his friend will offer to play gambling games that he installed on his smartphone.
It is very important to build a relationship with your child without resorting to any prohibitions. Today you have banned your child from playing smartphone, tomorrow you banned him from watching TV until he learned his lessons the day after tomorrow you banned him from eating candy. In a week the child has adopted this experience and permanently denied you access to his private life.