Question: what are the major factors that contribute to drug use and sales?
Answer: Risk taking. Some people are more drawn to risk taking than others. ... 
Predisposition. It may be that your genetic or psychological characteristics mean you are more likely to take drugs.
Experimentation. ... 
Gender and age. ... 
Hedonism (the 'buzz') ... 
Peer group. ... 
Availability. ... 
Family, social and environmental factors.