Walking around my city recently, I’ve been experiencing an odd and dislocated feeling of vertigo, as though the world is veering on a precipice and, without wanting to sound too dramatic, we are approaching what pavement preachers refer to as “the end times”. My husband says it’s just a symptom of getting older, but I’m convinced my environment has something to do with it.

Day by day, aspects of the city have started to blend into one another: the same chains popping up to replace local businesses, the flimsy-looking, so-called “affordable housing”, the upscale student accommodation blocks with their own cinemas, all becoming uncannily homogenous. These act as a backdrop to the tents and mattresses of so many desperate, homeless people. Things just feel wrong.

Bear this in mind when you consider this small bit of news from picturesque Notting Hill, west London, where residents are engaged in a row with Instagram “influencers”, who they say have invaded their area in their quest for beautiful backdrops. The residents’ streets, they complain, are being turned into “personal photo studios”, with some Instagrammers even bringing along pop-up tents for outfit changes.

Search the hashtag #nottinghill on Instagram and you’re confronted with an explosion of pastel pinks and lilacs, as though a unicorn has vomited. Young women pose in front of houses and magnolia trees in matching outfits. Meanwhile, the creativity and diversity of the area is invisible, the council estates around the corner from these wealthy streets elided. One in seven people in the royal borough of Kensington and Chelsea is homeless. This is the borough of Grenfell. But this reality does not look pretty on a screen.

Now, would that we all had large Victorian terraces so desirable that our biggest problem was an attractive girl camped out on our doorsteps. But this isn’t really about the highly gentrified Notting Hill. The Instagram effect is changing the way people travel, dress, interact, live. It’s affecting mental health and self-esteem, and transforming the way multinational brands market to us. This app, which has more than 1 billion users worldwide, has changed the world, and will continue to do so.

And this is a mostly female-led phenomenon (there are male influencers, of course, but much fewer in number). I once thought the decline in influence of women’s magazines would be a good thing for young women, not realising that young women would step in to market insecurity to one other. These influencers have become living magazines, moving fashion models whose whole outfits can be purchased at the click of the button. They market us their highly staged “perfect” lives in the same aspirational way as magazines do, but with an added claim to authenticity – and despite studies showing that this has an impact on self-esteem, users eat it up.

Meanwhile, as the bleakly hilarious account Boyfriends of Instagram shows, the men in their lives are reduced to stage-hands and photographers in the fashion spreads of girlfriends’ lives. I’ve seen couples arguing at beautiful sunsets because, having taken 50, the girl wants “one more photo”. Some men now refuse to participate at all. Then, when babies come along, they are incorporated too.

Perhaps this all seems trivial. If you’re young, perhaps you don’t participate it in it, and so don’t see it as a problem. My undergraduate journalism students are highly critical of social media. Besides, you don’t have to follow. I use Instagram quite happily to communicate with friends, having unfollowed anyone whose photos consist mostly of pictures of themselves. I’m sure I’ve posted the occasional naff photo, as so many other users have; but it doesn’t mean we buy into it wholesale, right? And if you’re old, perhaps it’s just another sign of the vacuity of modern life. Nothing to get too het up about.

But I’m starting to worry that the dangers of Instagram could be bigger than even its impact on mental health. The shift towards the self must surely come at the expense of more societal, collective impulses. It certainly ruined a music festival I attended last summer: the whole thing was engineered towards posing for photographs: essentially, a series of backdrops in a field. For the punters, engaged in competitive “festival dressing”, the music seemed barely a factor. The collective experience felt wooden and diluted.

Instagram is already changing the way humans interact with culture (see also selfies in art galleries), but it goes beyond that to their physical environments, the way users walk the streets and navigate architecture. How long until those mattresses and tents and the homeless people occupying them become entirely invisible? I wonder how this social media selfishness is going to mutate, and whether it will come to affect how we do politics. It may have already contributed to Donald Trump and Brexit.

And yet I am hopeful. A recent appraisal of the legacy of the comic Bill Hicks seemed to suggest that his scathing anti-advertising stance was outdated, but I don’t think it is. He was accused of sneering, but I’d like the historians of the future to know, as they pick over the debris, that some of us were kicking and screaming. Reassuringly, there are still 6 billion humans who haven’t signed up.

• Rhiannon Lucy Cosslett is a Guardian columnist