Well I can tell you from personal experience...my son...was a very good athlete in HS, started smoking pot...in college, tried oxy and that ilk, graduated to heroin, six years later he's dead...most of his buddies in recovery, pretty much took the same exact path. He never liked alcohol, but probably had an addictive personality. Whatever he loved, he was obsessed with, basketball, heroin, weight lifting...all done to excess. Going directly from weed to heroin I bet is rare, there's lots of stuff in between. But at least in his case it all started with weed.
Don't want to be a thread killer with that post. Actually I'm very interested in what most people who have not been affected by this crisis think. I smoked a ton of weed as a youngster, but that was like 40 years ago. Times have changed, I was never really "anit-drug" (meaning pot), now I'm pretty much anti everything. If Danny would have stuck with pot, that would have been no big deal in my book. He didn't stop there though, and his story is not uncommon.