I think all types may be attracted to substance abuse for their own unique reasons. SPs may simply be experience-junkies who feel a need to try everything once. SFJs might want to do it to "fit in" or because it's "what the cool kids are doing." INTPs likely aren't interested in that, but are more likely to be interested in the consciousness-expanding properties of drugs. We may see drugs as one big consciousness experiment; almost as a form of first-hand information gathering, with life as the laboratory. We may also drink heavily to fit in with social circles we normally don't just to see what it's like (kinda like spying on the enemy
). Curiosity, boredom, and a lack of commitments (unlike J-types) are likely what may drive us to substances.
However, I'd say we're probably less likely to become easily addicted, although we may lack the willpower of a, say, INTJ, if we happen to become addicted and try to quit. Obviously genetic factors are what primarily determine tendency to addiction, but strictly on type alone, I'd say our tendency to become easily bored with things would seem to generally discourage the forming of addictions.
Personally, I've never been addicted to anything, although I have found it hard to change my sleep habits when I have to. Like REALLY hard. Like it makes me feel like I'm sick. I drink coffee, but can go weeks without it no problem. My parents have always been addicted to coffee though, and "have" to drink it daily.
I'd say my Ti is much too active to let me unwillingly become an addict, as I'm always super-aware of what I'm doing at all times.
(young probably)
