I am a serious nicotine addict and I disagree! I thought the same as you, but over the years I’ve managed to quit easily for months and years at a time. The hard part is not starting again which at least for me usually coincide with too much stress
Addiction works differently for everyone. I drink coffee constantly but I can stop with ease. Maybe an occasional headache. I have a friend who describe her ordeal of quitting caffeine and it sounded almost as bad as my struggle when I quit nicotine.
For me, when I was smoking a pack an half a day, the idea of stopping temporarily was incomprehensible. I smoked through root canals, strep throat, countless head colds, you name it. All of my quit attempts, including the successful one 5 years ago were like a waking nightmares that made my life a living hell. Maybe your experience is different. Many people's are.
I have a similar experience: I can quit in three days provided I'm relatively stress-free and not the companion of a regular smoker. I can stay quit for months, even years, but particular stresses knock me off the wagon.
One cigarette is all it takes; it's not a slippery slope, it's sheer cliff.