The 'thrill' of the chase... The anticipation... The score...
I'd get more adrenaline pumping through my veins before even using sometimes.
It's the Pavlov's dog thing, you know.
The drugs and booze are an infinitely tiny marker of what it is that really makes me an addict. That I absolutely need to satisfy my inner attention junkie, even in the face of overwhelming evidence that the behaviors I engage in are dangerous, is a much better indicator.