In short, childhood trauma and lack of family support. Often the trauma comes from abuse from their family. These are not problems you can just throw money at.
> I question how much experience you actually have with either the poor or drug addicts.
If you must know my experience I did youth work for inner city kids from 1999-2006 in Langley BC. I then lived and worked in the Vancouver DTES from 2006-2017. I have several close friends and family members who work at Insite Injection Clinic, Portland Hotel Society, HIV/Aids Clinic at St. Paul Hospital, and the Odyssey and Nexus programs in downtown Vancouver.
Perhaps you are unaware what life on the streets is like.
Edit: also, I never said I was a "majority" that has an expensive addiction. I said the number of people is significant - which it undoubtedly is.