Google cofounder Sergey Brin played a key role in the development of Google's Gemini AI model. Kelly Sullivan/Getty Images 2025-05-21T00:04:07Z Save Saved Read in app This story is available exclusively to Business Insider subscribers. Become an Insider and start reading now. Have an account? Google cofounder Sergey Brin just made a surprise appearance at the company's I/O conference. Brin said he's back at Google "pretty much every day now," where he's been developing AI products. Brin also spoke about why Google Glass failed, though he's bullish about Google's new XR glasses. Google cofounder Sergey Brin made a surprise appearance onstage at the company's flagship I/O developer conference Tuesday, where he explained why he's returned to the tech giant and what he's learned from the failure of Google Glass over a decade ago.It's the latest sign that Google is going hardcore on AI. Brin has been back at Google to help develop its AI products since 2023 as the search giant races against OpenAI's ChatGPT, and he shared about what he's been up to since returning to the trenches.Brin wasn't expected to speak at the talk, which Google billed solely as an interview of its DeepMind CEO Demis Hassabis. He joked, "I torture people like Demis, who is pretty amazing. He tolerated me crashing this fireside."In the chat with Hassabis, Brin said he comes into Google "pretty much every day now" to chip in on training the latest models from Gemini. It's something that naturally interests him, the famously technical co-founder said."I tend to be pretty deep in the technical details," Brin said. "And that's a luxury I really enjoy, fortunately, because guys like Demis are minding the shop. And that's just where my scientific interest is."Since returning to Google, Brin also attended last year's I/O, where he fielded reporters' questions about AI.Learning from Google GlassAt the 2012 Google I/O conference, Brin famously demoed a video in which he wore Google Glass while skydiving to show off the tech giant's previous foray into wearables. This year, he also addressed Google Glass, which it stopped selling a decade ago. At the Tuesday fireside, Brin said Google Glass's failure stemmed partly from his lack of knowledge about manufacturing and supply chains."I just didn't know anything about consumer electronic supply chains, really, and how hard it would be to build that and have it at a reasonable price point," he said.Brin is far more bullish on Google's latest wearables venture: "XR," or Extended Reality, glasses. At the fireside chat, he said he thinks AI is far more capable now for such a product.Business Insider was able to snap a picture of the normally reclusive billionaire trying the XR glasses on before the fireside chat, too: Brin trying on XR glasses at I/O in 2025. Charles Rollet / Business Insider