Robert Downey Jr. became a drug addict by accident 

RDJ was arrested and attended rehab several times between 1996 and 2001 – insists he had always promised himself he would never try class A narcotics and only realised he had a problem when he used drugs to get rid of his “flu”-like symptoms.
Keywords: robert, downey, jr., became, A, drug addict, by, accident, jr, rdj