Why does an individual become dependent on drugs or alcohol?

(N/A) Dependence is the tendency of the body to manifest a characteristic and unpleasant withdrawal syndrome if the regular dose of drugs or alcohol is abruptly discontinued.
It is characterized by symptoms such as anxiety,shakiness,nausea,and sweating,which may be relieved when the use is resumed.
In some cases,withdrawal symptoms can be severe and even life-threatening,requiring medical supervision.
Dependence leads the individual to ignore all social norms to obtain sufficient funds to satisfy their needs,which results in many social adjustment problems.