Curiosity will always be the biggest driver for every gambler, especially for those beginners who have just come to gambling, usually curiosity will dominate him more and also on the other hand temptation will continue to make you even more crazy in putting that curiosity. This is the starting point that will determine whether they will end up with addiction or not, but usually gamblers who come because they see the victory of others will find it difficult to hold back every curiosity because yes, what is in their mind is winning not gambling for entertainment.
I think that greed is the bigger driver than curiosity. Curiosity is even triggered by greed in this matter. Unless the gambler is not in for profit, then it is an exemption but to be honest, almost all gamblers are aiming for a win. Like you stated, if victory of others lead a person to his curiosity, then more likely that person aims to win an amount which can be said to be trigger by greed. So this simply means cutting off greed can make a gambler less likely to get hooked in gambling.
One of the things that they must have and emphasize on themselves and especially on their mindset is to apply self-control very firmly, they do not know what kind of temptations exist in gambling sessions, so it is the right action in general to be able to save them from things that are not wanted, especially losing large amounts, and also yes so that you avoid the name of a very bad addiction. There is no other way to overcome the disastrous effects of gambling, only self-control and strict limits, I hope you and they can implement it well.
I agree and one that can ensure that the gambler can apply a self-control is nullifying greed. Greed makes one to think irrationally, it also makes a person to chase winnings which is harmful in the end since it can make a gambler spend more than he can afford to lose to meet his goal.
In addition time moderation is always important and make sure that a person must not forget his other responsibilities and obligation. In short, don't let gambling be the center of his life.