I totally agree with the statement itself, but my experience around many stoners is similar to IsaacL's: they're generally not happy or relaxed at all, and smoke weed because they're stuck somehow (or vice versa, perhaps).

More often than not, the 'relaxed lifestyle smokers', myself included, did so primarily to numb the stress in their head, whether caused by work stress, personal issues, social anxiety, etc.

Basically, it's often more to cope than to relax, at least in my experience and that of my surroundings.

But exceptions always exist, of course. I just think it's good to be cautious with anything that seems to offer a quick solution to a difficult problem (being at peace / relaxed).