An addictive personality. Do you think the mind-set leads to addiction, or does the addiction lead to the mind-set.

I got to thinking about people who have gone downhill...in the grips of any addiction...does the addiction lead to their demise...or was it just the way they are...their mind-set..that ultimately leads to the addiction... While it's not easy to explain...one could more or less say: Where does the fault lie?