Gambling becomes dangerous when people continue to chase losses until they become severely addicted, leading to financial ruin and ultimately depression and mental illness.
It's just that when things like depression kick in, it's a very delicate thing for a person. The most delicate cases are those because the person usually can't find a solution, Some commit suicide and believe that's how they'll fix it, I think that when there are very Strong symptoms, help should be immediate You shouldn't think about what to do, but rather act quickly. A life could be saved.
Though what you said is true, in real situation, the victim or the person that's addicted to gambling is not fully aware that he is still in control and won't really see the symptoms until it's too late. Sometimes the person won't really notice it and thus result to depression and suicide, so it's better to have someone to check up on you, or while you are still capable, stop playing and if you really can't stop, then it's time to go see a therapist before it's too late.
Usually someone who is addicted doesn't know they are addicted until they started affected the next people around them, and again when they found themselves too much attached to what they are doing or and can't limits and take break from gambling then we should know they are addicted to gambling which is tantamount and equivocally of seeing the therapist for a solution and remedies.