As for me i think the parents owe the children nothing to explain for them as long as they never let the vacuum of their responsibilities in training the children remain void, when your children never have access to gambling or where they do such then you owe them no explanation, parents have their own part they play from their children way of upbringings, they must not engage doing things that we will not be aware of which may affect them in life the wrong way.
You can’t control or limit your kid to have access on gambling since internet makes it accessible to everyone while most of the kids on this generation can't leave without gadget and internet since it's the new way of communication and learning things.
As parent, I think it's more suitable to educate your children about potential risk of doing instead of discovering it by their own and experiment on it out of their curiosity. This is the common mistakes of parenting, They don't want to tackle things like this that eventually being discovered by their children by themselves and secret this from their parents.