José Lucas Costa da Silva peered over towards the warm-up area for the Brazilian jiu-jitsu competition he was about to referee, faintly amused. It was early May 2023, and the 26-year-old martial arts instructor watched as one competitor in the high-school sports auditorium stretched and ran drills. He was wearing a white “gi”, a robe-like uniform, with some unusual accessories: sunglasses, a dark blue baseball cap and a medical mask. The man, whose name was listed as Mark Elliott, was a white belt, the beginner rank.

The tournament was taking place in Woodside, an affluent town close to Silicon Valley known for its sprawling estates enveloped by redwood trees. Da Silva, who is a jiu-jitsu black belt, sometimes trained the neighbourhood’s nerdy, deep-pocketed residents for a fee. When the time came, da Silva beckoned Elliott and his opponent over. Only then did Elliott take off his mask and shades. A buzz swelled in the hall, as people in the audience pulled out their phones to film. Da Silva noticed there were security guards in the periphery. “That’s when everyone realised he was there,” he said.

Mark Zuckerberg, the billionaire founder of the world’s largest social media company, Meta, had registered for his first official jiu-jitsu tournament under his first and middle names. He had been preparing for this moment since he got into martial arts during the Covid-19 lockdowns. In the years since, he had trained hard, hiring celebrity instructors to come to his Palo Alto mansion and his compound in Hawaii, working out each day. Now he was ready to show off the results.