IMO the chemical addiction just acts as a mechanism to enact the escapism. Like with a cigarette I could shake my brain like an etch a sketch, switching to a new mental scene, by blasting it with dopamine.

Also, when I was out of cigarettes I had a mission: get cigarettes.

That chemical dependency thing just adds a new magnet to the mental filings so they align less along the lines of feeling bad about my life.

A drug habit is like a video game for your emotions. You assign yourself this arbitrary quest, and a whole set of missions and adventures come out of it, and it kills the time.