As a psychologist and addiction specialist for more than 25 years, I have learned that there are so many factors that influence whether one will reach out for treatment for an addiction, psychiatric disorder, or perhaps the combination of both. Janis and Mann (1977) reflected on this with their "Balance Theory," which looks at the pros and cons of changing or holding onto certain behaviors (regardless of whether the specific disorder has a genetic predisposition or not).
For example, perhaps an individual is self-medicating an anxiety disorder with alcohol - has their use of alcohol started to cause more problems then it is worth as an "elixir" to sooth their apprehension? Is the person in a state of denial (what Prochaska and colleagues  refer to as the "precontemplation" stage of change). These two factors alone warrant the person reaching out to help someone to meet them where they are at.
This does not mean that some gentle nudging or even a formal intervention are not effective tools in one's clinical armamentarium, but it is always important to hear what the identified patient (defense mechanisms and all) has to say. It is like being a bit of a detective - understanding the nuances of each individual's behavior.
Perhaps the best thing to do when trying to engage someone in treatment is to leave it to the professionals. But even then, the professional must treat every person with dignity and respect and not shame or blame them for any particular disorder, but instead hold them responsible for dealing with it. Remember just because someone has a problem does not mean they should not be held responsible for dealing with it - what this author originally labeled "Carefrontation" (1990). "The road is paved with good intentions" is a great saying but so is "think before you act"!