I referred to it as a trend before, but really I think of hipster as a subculture comparable to punk or hippie. As a subculture, it has to be evaluated on its own terms. There is a parallel between hipsters and hippies, as the name implies, but punk is a whole different thing.

A mere trend doesn’t go beyond aesthetic; there is no ideology to high-rise pants or plimsolls, although both of those aesthetics might be used by this or that subculture. Aesthetics wax and wane over the years (largely driven by corporate fast fashion, but that’s another discussion) but that movement is perpendicular to culture and ideology as such.

Being a hipster is the ideology of being a hipster, not just the aesthetic preference for thick-frame glasses and beanies. It was the rejection of the mainstream by a particular demographic, largely white urban/suburban youths, and replacing that with a distorted image of the imperial periphery. The periphery isn’t only geographical; it can include neglected communities inside the core itself, such as hillbillies and indigenous tribes. In a way, it continues a long history of psychological fixation by the privileged classes upon the underclasses. They have always been fascinated about life outside the garden, and that fascination manifests in imitation.

I think that's mostly down to hipsters existing back when there was still somewhat of a monoculture. Nowadays everything's so fractal that nobody even knows what to hate on.