Addiction to any given substance is highly variable from person to person, and there's a lot of data to back that up.
I recall a friend describing their struggle to quit caffeine, which I mocked at first, until I realized it sounded exactly like my brutal struggle to quit nicotine. Yet, plenty of people quit cigarettes effortlessly. Nicotine is one of the most variable, but caffeine, alcohol and cocaine vary widely too. I imagine we'd find this is the case for most substances if we had the data. In a sane world, we'd give every kid their addiction predisposition profile when they turn 13.
The hardest part of quitting anything is changing the behavioral habits that came with it.
For smoking, I bet you have the urge after a meal to smoke. Maybe you’re triggered when you drive long distances to “calm the nerves”. The issue is those triggers, those behaviors, need to be unlearned before you can attempt to quit. That’s why it’s easy for people who haven’t developed those behavioral habits and hard a hell for those who have. Former smoker myself so I totally get it. I can give that up, but caffeine - coffee? I’ll die with a cup on the counter half full.
The literature on this is clear cut. People absorb, metabolize and experience drugs differently, which has a big impact on how addiction takes hold. It's obviously not the only factor! But it's a big one and somewhat quantifiable.
Personally, I wasn't a "trigger" smoker, I was an "every chance I got smoker". I assume my nicotine metabolism is higher than average, which is linked to frequency of consumption and hence propensity for addiction. I also assume I have fast caffeine metabolism since I consume it at all hours with no consequence, but unlike nicotine that's linked to a lower propensity for addiction, which matches my experience.
I recall a friend describing their struggle to quit caffeine, which I mocked at first, until I realized it sounded exactly like my brutal struggle to quit nicotine. Yet, plenty of people quit cigarettes effortlessly. Nicotine is one of the most variable, but caffeine, alcohol and cocaine vary widely too. I imagine we'd find this is the case for most substances if we had the data. In a sane world, we'd give every kid their addiction predisposition profile when they turn 13.