If you win - usually you'll get a thrill (associated with neurotransmitter/neuropeptide release) which across a long term creates a positive feedback loop leading you to enjoy gambling and continue to do so. Furthermore, if you gamble regularly you reinforce the habit - so regardless of how much you enjoy it you'll be more inclined to gamble.
You're correct! However the explainition is quite vague ,to be specific on how exactly addiction takes over the control of human body
consider this :
Addiction is a primary, chronic disease of brain reward, motivation, memory and related circuitry. Dysfunction in these circuits leads to characteristic biological, psychological, social and spiritual manifestations. This is reflected in an individual pathologically pursuing reward and/or relief by substance use and other behaviors. Addiction is characterized by inability to consistently abstain, impairment in behavioral control, craving, diminished recognition of significant problems with ones behaviors and interpersonal relationships, and a dysfunctional emotional response.