I do so enjoy the hobby-not hobby debates!
I'm a smoker who doesn't find smoking particularly interesting, It's simply a wee vice I selected years ago. I have hundreds of interests in life. I drive a vehicle, always interesting. Being most likely "obsessive-compulsive" I can't keep anything at the "hobbyist" level. I read books, play musical instruments, photograph wildlife, mow the grass, move snow, enjoy my grandson, cook, eat when necessary, fish, research items of interest ... I could go on but, ... I see no point and do not understand why anyone would find my particular interests of interest.
To me, the very idea of burning up one's hard earned cash while engaging in a totally unwholesome and unhealthy, though enjoyable, activity is ... well, the antithesis of a "hobby." At least in my opinion. Although, I've heard of some who certainly consider some self-destructive behavior to be "hobby-like." Masochists and sadists come to mind.
I think smoking is considered to be a hobby only by those who can't/won't admit to being a smoker. I would exempt those who honestly do collect, those who seriously explore blends and the dabblers who smoke a bowl or two a month or every fifty years. The latter are simply dilettantes in my opinion.
Then there are those who will open a drawer, find some old used pipes and wonder what they were thinking when they tried smoking.