I highly agree with you, the best way to keep young ones from being ruined by gambling is to have proper knowledge about gambling. Forbidding them without telling them the reasons can only fuel their curiosity which can lead to devastation. Giving them seminars and a deep understanding of gambling and its effects will give them a natural resistance to gambling addiction. They should be properly guided by the older ones since I think that gambling exposure is inevitable due to technology. With just a simple click or touch kids can enter the gambling environment so it is best to equip them with knowledge about gambling than secluding them away from gambling.
I do not think parents can control their kids' access to technology. And by not giving these kids allowances, this will be make a wall between parents and child, I still think the best approach is guiding our kids on what to do with gambling.
As a parent we cannot control everything, the best we can do is to guide our children to have proper knowledge on how to carry themselves and have self control over their actions.