I defy anyone who likes heroin to continue casual use once they find a reliable supply...
All I can say is I personally know several. In fact, a good handful.
And what distinguishes those people from the junkies isn't the supply.
It's their motivation for using.
Drugs don't inherently contain 'addictiveness'. That's not a chemical property. That happens inside the mind of the individual user.
Heroin was once my lifeblood and my everything. My only joy, only peace, only comfort; my daily need. Now it's merely one of life's many pleasures.
Heroin is still the same drug. I am still the same person. Nothing has fundamentally changed except for my relationship to that drug.
You, by your own account, went from long - term chipper to junkie. I went from paid - up junkie to chipper yet I still got all my contacts and could score whenever I felt that way inclined. I've been a casual user for exactly one year longer as of now than I was a compulsive user, and have never felt the slightest temptation to go back to my past ways.
On the other hand, I'm being offered coke and crack and meth more or less on the daily. Drugs that are supposedly as 'inherently addictive' as any of the opiates. Well they've never done anything for me so no amount of opportunities for acquiring them is gonna make me a stimulant addict.
By the same token I've known someone to try an opiate and either get ZERO effect, or absolutely hate the effect they WERE getting.
I also know a fair few stimulant users that are TOTALLY sold hook line and proverbial sinker on their DOC.
It's nothing simply to do with ease of access. It's nothing simply to do with the chemistry of any particular substance.
It's EVERYTHING to do with how well do you individually respond to the drug; what do you want from it , and does XYZ seem to give it to you. That's where addiction begins and ends.