Narcissistic Supply refers to those people who provide a constant source of attention, approval, adoration, admiration, etc., for the narcissist.  The attention they receive from supply is vital for the survival of the narcissist, without it they would die (either physically or metaphorically), because their weak ego depends on it in order to regulate their unstable self-worth and self-esteem. The narcissist is engaged in constant self-avoidance, and narcissistic supply is their drug. 

The narcissist’s inner being (the True Self) is damaged. When the cracks appear and the abuse begins, this is the real person you meet. The inner self has trapped within accumulated childhood wounds that the narcissist has tried to divorce him or herself from. Narcissistic supply is the distraction. Never learning in childhood to be resilient or self soothe, narcissists develop no conscience or empathy. They do not love themselves, others, or life itself. This is the basis of all addictive behavior. A separation from self-worth, self-love and the ability to inwardly emotionally navigate life healthily.