As a drug, heroin really comes into its own when your life sucks and it serves its function as a vessel for escape. If you use it recreationally when things are going fairly well, you'll probably think This is it? This is the beast? Kinda cool, but I keep puking...not really worth it. Other drugs have made me feel much more euphoric and go on with your life. You'll probably go a few months, or even years, like this, doing it opportunistically and each time moving forward without much difficultly. You'll have convinced yourself that you have the self-control to handle heroin.
But then you'll have that magical time when you come across heroin during a rough patch in your life, and you think like this: Wow, I guess I was making a big fuss out of nothing. My problems are completely manageable. I just need to fall back on heroin every once in a while to slam things back into perspective for me. You'll come up with some magical plan about doing heroin 'often enough to keep your problems in perspective,' but 'not often enough to get physically hooked.'
But where things will go wrong is eventually the problems you're using heroin to put into perspective will actually be caused by heroin. It could be anything from a friend giving you the cold shoulder when he finds out you use heroin recreationally to getting a possession charge before you were even physically addicted. The point is that once you start using heroin to treat problems that only exist because of the heroin, you're screwed. This loop soon leads to physical addiction, and once you're physically addicted, it's very hard to stop, as heroin withdrawal is extremely physically painful. At this point, you're a heroin addict just like the people you see on the streetcorners when you go into the hood to buy your drugs. You just haven't gone through the process of losing everything you have to the drug like they have. Yet.
You'll soon run out of money, but the physical addiction will still be there. At this point, you'll have been exposed to the habits of a lot of career-addicts, and you will know ways to scam money and keep the habit going. You won't worry about being caught stealing from family/friends, about destroying your credit, about avoiding bills, about pawning off stuff you've had for your whole life, as the fear of the withdrawal will always be worse than the fear of the consequences of any of those actions.
Eventually something will happen that will force you to quit. You'll be arrested and not immediately bailed out. You'll be sent to rehab. Your dealers will all dry up at once. After you get through the withdrawal, you'll start to feel normal again, but you'll be overwhelmed with the guilt and the shame of having destroyed everything in your life, and you'll be faced with tons of practical obstacles in the way of getting your once-comfortable life back on track. It will be a tremendous task to get that life back, and you'll get bummed out over how long it's taking. And then one day heroin will fall into your lap, and you'll want to use to just get a few hours of escape away from the pains of having to rebuild a life destroyed by drugs. Cycle repeat.
