They are warning that something is wrong. Someone may even have the unmitigated gall to talk about the problem. When someone does this, the chemically dependent person hammers him or her. It's your problem. The lies escalate and the addict begins to get caught in the lies.
People challenge the addict with the truth.
All of this leads to more drug use, and the cycle goes on. Finally, some crisis brakes through the lies, some glimmer of the truth seeps in, and the addict comes into treatment. They are still in denial, still lying to themselves, still can't see the full impact of the disease. Drug abuse is the third leading cause of death in this country. Most people who are chemically dependent die of it, very few make it into treatment.