In 2017, James Dacombe dropped out of high school to found brain monitoring startup CoMind. Four years later, he took a Thiel Fellowship to skip college and build his first startup. Now the 25-year-old is Europe’s youngest self-made billionaire thanks to his two-year-old chipmaking company Olix, as well as an undisclosed stake in CoMind—which he still runs separately. Founded in 2024, Dacombe’s London-based Olix tripled its valuation in six months to $3.3 billion in early August, after raising $312 million from investors including NYC-based investment firm Fundomo, Nasdaq-listed chip designer Arm, American quant fund Hudson River Trading and Netflix cofounder Reed Hastings. The UK government’s Sovereign AI fund also backed Olix in the round. The new round pushes Dacombe, who owns an estimated 30% of the company, into the three comma club. He also has a 12% stake in CoMind, which raised $102.5 million in August 2025 but did not disclose its valuation. Olix and CoMind did not respond to Forbes’ request for comment.Dacombe is one of eleven self-made billionaires in the world who have yet to turn 30 and one of just four from outside the U.S.The next youngest self-made European billionaire after Dacombe is Arvid Lunnemark, a cofounder of popular AI code editing company Cursor. The Swede came to the U.S. to attend MIT and cofounded the firm with three college friends in 2022. Now a San Francisco resident, Lunnemark, 26, and his three cofounders all nearly doubled their fortunes to an estimated $2.4 billion on Friday, after SpaceX acquired Cursor for $60 billion. Cursor’s oldest cofounder, Pakistani citizen Sualeh Asif, is also 26. Coincidentally, there is yet another 26-year-old Swedish billionaire whose fortune nearly doubled earlier this week. Lovable’s cofounder Fabian Hedin, who lives in Stockholm and is just a few months older than Lunnemark, became a billionaire in December when his vibe coding startup raised funds at a $6.6 billion valuation. Lovable announced earlier this week it raised another $400 million round at a $13.3 billion valuation, nearly doubling Hedin’s net worth to an estimated $3.1 billion.These young titans are part of a global startup boom that’s minting younger and younger billionaires at a breakneck speed. In the United States, the title of youngest self-made billionaire has changed hands several times in the past year alone. Currently, the youngest self-made billionaire in the world is American Surya Midha, who was 22 when Mercor, the AI recruiting startup he cofounded, raised funds at a $10 billion valuation in October and boosted his net worth to an estimated $2.2 billion. Midha edges out his cofounders Brendan Foody and Adarsh Hiremath who are each roughly two months younger. (They are now all 23.) Midha took the title from Polymarket's Shayne Coplan, 28, who had taken it weeks earlier from Scale AI's Alexandr Wang, 29. Dacombe’s big bet is on the idea that it doesn't make sense to use Nvidia’s powerful AI chips for everything. Instead, his plan is to develop chips that are specialized for different parts of an AI model’s inference stage—when the model comes up with an output—as opposed to using only one type of chip. Its chips are also photonic, meaning that data moves between them as light instead of electrical signals, helping reduce delays and power consumption. It also deliberately avoids expensive, high-bandwidth memory hardware—currently in short supply. Olix plans to have them in customers' hands by the second half of 2027, according to a company press release. There’s a growing field of rivals. Silicon Valley-based d-Matrix is backed by Microsoft and already selling its Corsair chips, while startups like MatX, Etched and London’s Fractile have also raised big rounds in the past year. Nvidia’s also getting in on the action. In December, the chip giant signed a $20 billion licensing deal with Groq–a chipmaker founded by Jonathan Ross, who worked on early deals for Google’s TPU AI chips. Dacombe, despite never having worked in the chip industry prior to founding Olix, seems to think that his experience with CoMind’s photonics could give his new startup an edge over Groq and other chip giants. There’s plenty of money to fund all these ideas but the jackpot will go to whoever’s technology wins.As Dacombe recently told the Financial Times, “Today, where there is such an economic prize from being able to run very large powerful (large language models) fast and to a large number of users at a low cost, it really pays to disaggregate and have custom silicon that is good at that.” More From Forbes