Why some people don't want to own a smartphone?

I know a few people that don't want to own a smartphone. They're the kind of ''underground'' people. They do have the money; they just don't want it.

I'll give you an example. There are three guy friends who frequently visit our local pub. I see them often because I regularly go there to catch a coffee with my friends, and we're on good terms. They're not broke or anything. They don't want to own a smartphone. One of them has never heard of Whatsapp. They usually talk about instagram as if it's a board for idiots. They're very philosophical and well-read - but they only read classics. They aren't hipsters; trust me, they dress up maybe even too casually; but not fashionable or anything.

Well, all of them own an old nokia or samsung phone from maybe 2007. Two of them don't have a Facebook profile (nor any other social media profile). They're also not some outcasts; all three of them are very mannered, attractive and intelligent. They're educated (all three had studied and graduated IT on university). They're strictly against All networks (dating, social, guides, photography, etc).

Why do you think it's like that? Do you think it's prepotency? Is it vanity of some kind? Why wouldn't they want to 'adapt', as there are many apps that could make your life a little easier; like the travel apps? How would their employers feel about it?

Apart from smartphones; none of them own a TV either. They have computers, though.
Added (1). Sorry, but English is not my primary language. :)

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