As far as I know there are very few people who become addicted to gambling and share it with their family or others. What we typically see is that no gambler shares their addiction. They try to keep it secret as much as they can. A gambler will surely get a good solution when he shares this matter. Hiding only increases the problem so it is very important to share with others as much as possible. In some cases, it takes a long time for gamblers to identify the problem, so it is not possible to bring them back in time.
And the worst part is that gambling addiction itself can be very easy to hide, unless you were taking a look at the financial statements of the addicted gambler you will have no way to know that they are going through some financial problems.
While when it comes to other addictions it is very easy to tell at the early stages that there could be something going on that you are not being told, and this aggravates gambling addiction to the point that when those people finally ask for help, the consequences of their addiction are too severe and it will be difficult for them to ever make a full recovery.
On this point I agree with you, it is very true. Gambling addiction is very different from other addictions such as drugs, which is clear by just looking at the person we might already know he is a drug user, but for gambling it is not like that. Gambling operates below the human consciousness, and the effects of addiction are also barely noticeable. It involves the feelings and psychology of each person, only they know about their addiction, and maybe their close friends also know but not for others. I am an active gambler but not too much, and I have a friend who is very ambitious and gambling, he is so addicted that he seems to consider gambling as part of his life. I'm sorry to see him when his finances really fall apart because of gambling, I will always try not to get too far into gambling. So the point is that only the person themselves will feel the impact of their addiction and other people will not be able to see something that they are suffering from because it is not the physical impact that they feel but the mental and psychological.