Because all there focuses are on gambling, when you come across this kind of people. "all you need is to counsel them" because it's beneficial
If you are not someone who is close enough to a gambling addict, your advice will only be ignored. You should know that gambling addiction, which has already had quite severe effects, will not be easily eliminated just through advice. You may actually be considered someone who does not support them and will be avoided.
If they live in an environment that is also mostly made up of gambling addicts, then it will be difficult to make them aware. The influence of the environment is very important in forming a new, better awareness.
You made a very key point that is mostly ignored by many, Environment, the influence this can exact on us sometimes are very much that you may not be able to escape it and this influence comes gradually, builds up until a point where you get consumed already without knowing you are going that far with your new habits all influenced by your environment. I know of some one who lived in am environment where he had very easy and quick access to alcohol at any time of the day, the moment he moved out of that environment due to some constraints, his alcoholic addiction reduced so drastically you will almost not believe this person was once an alcoholic.