When Anna Wiener first moved to San Francisco for a job at a web analytics startup, she rented a room on Airbnb and found herself captivated by the idea of living amid another person’s belongings – their toothpaste, their soap. “I liked examining someone else’s product selections, judging their clutter,” she writes of her brief stay in an apartment that, she learns, was owned by one of Airbnb’s founders. “I wasn’t thinking about how the home-sharing platform might also be driving up rents, displacing residents, or undermining the very authenticity that it purported to sell.”

The passage is an apt description of the book itself, a memoir that presents itself as an outsider’s look at Silicon Valley – a jaded naif’s journey into the heart of venture capital. Wiener was a 25-year-old member of the New York literary establishment’s “assistant class” when she was seduced into the world of startups. In tech, she realised, people her age could be involved in building the future instead of fetching coffee for the quickly receding past.

After the web analytics startup, she moved to (the unnamed but barely disguised) open-source platform GitHub, which was acquired by Microsoft in 2018 for $7.5bn. Before she burns out and cashes in her stock options, our narrator gets an education in the world as imagined by confident and careless young men, or, as she puts it, “immersion therapy for internalised misogyny”. Wiener’s judgments are cutting and satisfyingly wry. “They engaged with their new home by rating it,” she writes of her fellow tech workers in San Francisco. Incisive commentary on the aesthetic excesses of the successful abound; the book’s first half unfolds like an exquisitely curated Tumblr blog, with a scroll of beautifully juxtaposed snapshots of the young, newly wealthy and utterly absurd.

It’s in the second half that the book feels frustratingly, and at times startlingly, thin. Wiener’s admission that she did not like to think about the societal implications of her choices is inadequate, and the degree to which aesthetic judgments supersede ethical or moral considerations grows wearying. Her friendship with a billionaire CEO coyly identified as “Patrick” (that would be 31 year-old Patrick Collison, CEO of payments company Stripe) offers an opportunity for her to lay her political cards on the table, but she largely refrains. In 2018, Collison’s company gave more than $400,000 to oppose a local business tax that would have funded services for the city’s homeless. In the book, his gravest transgression is having a birthday party in the woods but not sticking around to camp out.

San Francisco’s large homeless population is impossible to ignore. During her tenure at GitHub, Wiener describes observing a homeless man wearing a hooded sweatshirt branded with the company’s logo while on her way to work. (The encounter is not the first time our narrator has remarked on the visual dissonance of a person in poverty wearing tech industry swag.) Wiener admits to feeling “disturbed” by the sight of the beggar for the rest of her commute. “The man seemed like a novelistic apparition, a hallucination,” she writes. She tells a co-worker: “It was the city’s socioeconomic gap personified, I said. It felt even more significant that the man in the light-rail station was black, and not just because San Francisco was losing its black population at a rapid clip. To my knowledge, the company had just two black employees.” The co-worker deems the situation “sad”, then adds: “I wonder whose it was … We’re not supposed to give away the hoodies.”

What are we to make of moments such as these? I can see how this might be intended as another cutting observation of the clueless tech bro in his habitat, but 200 pages in, I found myself struggling to swallow bitter ironies about human suffering as eagerly as I had witty remarks about bespoke cocktails and startup office furnishings. The amoral cocoon within which Wiener and the rest of the tech industry reside is pierced with greater frequency as the book proceeds towards the November 2016 election. Discrimination in the workplace, antisemitic trolling, Gamergate, structural racism and sexism become topics of concern, but not ones that she shows particular interest in engaging with. They are instead presented through the same approximate frame as the homeless man in the hoodie – as problems that make Wiener feel uncomfortable; opportunities for irony not empathy. When a repository of files related to the debunked anti-Hillary Clinton Pizzagate conspiracy theory spread by the far right shows up on GitHub’s servers, she shrugs. “I didn’t know what I was looking at, and didn’t want to. My teammates seemed to have it under control.”

They didn’t have it under control. These days, amid the consequences of the surveillance, harassment campaigns, discrimination, extremism and nihilism that the tech industry fostered, it is natural to wonder how we got here, and why more people haven’t done anything to stop it. It is here, perhaps, that the book feels less like an outsider’s account and more like an insider’s unwitting confession.

• Uncanny Valley is published by 4th Estate (£16.99). To order a copy go to guardianbookshop.com. Free UK p&p over £15.