This is the reason that I have always said that the best way to cure a gambling addict is when the person realise that they are very much addicted and the person involved who is the victim understands that they need help. That is the fastest way to rescue someone who is addicted. If someone is truly addicted, but they do not understand that they are addicted, all the effort you put in stopping the addiction will result to nothing. Thereby rendering their efforts fruitless. That is why it is fine to first convince someone that they need help before rendering help to them.
It's just a general thing. For someone to get corrected when they are wrong in their actions, they must first acknowledge that they were wrong before they will accept the advice you are giving them; otherwise, you are just beating around the bush, and they will still do whatever they have on their mind the moment you just let them go. There was this friend of mine in school who was so addicted to gambling that his parents tried a lot of strategies to help him get out of this addiction, but every attempt was futile, and I know the problem the guy has is that he has not really realized that his habit towards gambling is so terrible; only if he realizes it, then he will limit how he gambles.
Another reason why people who are addicted hardly realise their addiction is because they still derive pleasure in what they are addicted to. For instance, in gambling addiction, they are addicted and yet having fun in the gambling. So, they may mistake an early stage of addiction for passion until it is out of hand.
When one is addicted and still passionate in their addiction, it is very bad because the person might not be cured or rescued from addiction. The best approach is to start fighting the addiction from the early stage because once it is matured, it will be complicated to handle.