In the case of kids, I would never encourage them to earn money because if they rush towards money income at an early age, they will be held back by the natural growth that comes with age. Young children think of their parents as their greatest teachers. Whatever good and bad parents do in front of children, children try to imitate it attentively. At that time if a parent shares the gambling related matter in front of the children then they will surely imitate it and at some point they may be encouraged to gamble. So parents must be careful about these things in front of children.
Children tend to want to follow what adults do, usually their curiosity about something is very high, that's what ultimately drives them to want to do the same thing as adults do. I have a young nephew, when I play online games on my cellphone he always wants to be near me and watch the game and even they want to play too.
It's the same with gambling, when we gamble in front of them, I think they will do the same thing as what they are seeing. So it would be better if we stay away from them when they want to do something that based on their age they are not fully ready to accept or see what they should not see. It is our job as adults to always keep children from being contaminated by something that will interfere with their development.