Many addicts have an emotional void and are constantly trying to fill it with all the wrong things - buying stuff, booze, drugs, sex, serial relationships, etc. Often it is the result of childhood abandonment, betrayal or simply absence by the primary caregiver. So we are always seeking to fill that void. I read a great book a few years ago called "In the Realm of Hungry Ghosts" by Gabor Mate, which explains the concept.