I worked for 10 years in an outpatient center for emotionally ill adults, including recovering drug addicts and alcoholics, and had many a conversation with them. They quite frankly talked about how self centered they'd been, when involved in their consciousness altering behavior, indulging. The professionals sometimes call it self medication on account of underlying mental illness, like bipolar disorder or schizophrenia. I don't know.
I know we've talked elsewhere on this forum about the tendency in our culture to blame bad behavior on illnesses rather than to take responsibility for the behavior. We're becoming, or have become, a country full of "co-dependents", excusing people for their self centeredness, calling it a disease, and standing by while they devastate the lives of others. I don't think that alcoholism and drug abuse are victimless crimes. If nothing else, as my mom used to say, by buying drugs you're supporting the mafia.
Might drug addiction hinder spiritual growth? Getting high must be one of the most selfish activities that exist. It is done without regard for anyone besides oneself. Is that person's pain any deeper or more important than the pain of his family as they stand by and watch him destroy himself? I know that often times the drug abuser believes this to be the case. I've spoken to many a one.