So it appears that he is suffering from a disease. You are very correct in telling that drug addiction is a disease. It is in fact more than a disease as disease is curable but drug addiction requires lot of change in life style and a great dose of counselling before one can really get rid of this.
Those who are regularly taking it are actually escaping from the practical world where responsibilities are to be taken up and one has to work hard for mitigating the difficulties of life.
Knowledge is power.
I think people who are lonely by heart or living alone get more easily addicted to it. The reason is they don't get the right guidance either from their family. Drugs are bad for health physically and mentally both.
Those who are suffering from this addiction needs to be treated with patience, love, and care. One other reason that could cause drug addiction is an undergoing phase of depression. When depression is untreated and people feel helpless, they feel unheard from everyone close to them, they could get addicted to it.
Drug addicts need good counseling to help them come out of this tough situation.
Do what inspires you !!
'Idhuvum Kadandhu Pogum "
Even this challenging situation would ease
The parents should have a close observation of their wards especially during university education times and they should take the corrective action in the initial stages itself so that they can save their wards from this drug menace.
The drug peddlers are also very smart to target these vulnerable people and supply them for money or even exchange of valuable items or even sexual favours. Once the individual start getting used to it and moves on to higher drugs and volumes, they get addicted to it.
When they reach to point of addiction, then it is a disease. Instead of getting angry at them or neglecting them, they need professional help and lot of love and support from the families. It is difficult to beat drug addiction but not impossible. There are many celebrities, sports and movie star who have beaten drug addiction.