Not necessarily true. Mind over matter is one thing, but an addition that takes hold of your system like nicotine is another. A habit is a habit, an addition is a different ball park altogether. It's not all in your head, it's an addition that is programmed into your body as well as the mind.
However, I do have friends who are able to quit at the drop of a hat, and then there are those who couldn't if they tried. It all depends on the person afterall.
As for me, I'm one of the condemned. I've never smoked much more than 10 a day though. Wouldn't say I'm a hardcore addict like those who down 50 a day.