Sooner or later, they will addicted to gambling. Once that is happen, they will ruin everything they have and even their life.
Each gambling addicted is different. Being gambling addicted isnt something uncurbable and does not mean that everyone will ruin their lives with 100% probability. I think everyone who has tried gambling at least several times are already addicted, because they return to gambling anyway. We have different forms of addiction, someone return and gamble daily, someone on special occasions, someone gamble once each month. But that does not mean we all are moving towards ruining lives.
Ruining one's life just because of addiction can be the result of a lack of understanding and greed, especially when one believes so much in winning games in gambling. Addiction becomes very obvious when there is no threshold to gambling, and when it reaches a level so extreme that one can go to the point of doing anything for gambling. The result of this can always ruin one's life. That is why it is important for a gambler to be very careful and conscious about self-examination and to make some adjustments when gambling activities become obvious; if not, it will reach a state that is uncontrollable.