But the billionaire – who was recently seen announcing the move to change Facebook’s name to Meta – has a very lavish lifestyle.
Mark, who is worth a whopping $121.6 billion (£88.2bn), lives in a robot-butler-run house in Palo Alto, California, with his wife, Priscilla Chan, and their two daughters, Maxima, five, and August, four.
But that’s by no means the only house he has, as he now has a property portfolio worth $320 million (£232.3m), having bought many swish pads in California and Hawaii.
Mark also has plenty of celebrity friends, including Vin Diesel, and – although the grey t-shirts he regularly wears look like they could have been picked up anywhere, they’re actually quite expensive.
We take a look inside Mark’s surprisingly lavish lifestyle…
£5.1m robot butler-run mansion
In May 2011, Mark bought his five-bedroom, five bathroom in the Crescent Park neighbourhood of Palo Alto for $7 million (£5.1m).
Originally, Architectural Digest described the property as a “no frills abode” that chooses function over extravagance, although the house has a large back garden and swimming pool.
But Mark made some major renovations to the property, and now the mansion has a saltwater pool, sunroom, entertainment pavilion, fireplace, barbecue area, spa, a “Facebook Canon” that launches grey t-shirts out of it – and even a “custom-made artificially intelligent assistant” called Jarvis.
The robot butler – which has the voice of acting legend Morgan Freeman – can adjust the room temperature and make toast.
The robot even helps teach Mark’s daughters Mandarin – although Mark’s Chinese wife Priscilla recently admitted to The Times they “haven’t been terribly successful” at making the girls bilingual.
£36.9m Silicon Valley village
After he’d bought the first home in Palo Alto, Mark began buying the neighbouring houses around it.
He shelled out $50.8 million (£36.9m) in total for the area, which spans at least 1.83 acres, and has 15 bedrooms and more than 16 bathrooms in total.
He uses the other four homes as guest houses and recreational facilities.
In 2016, he proposed to demolish the four residences and replace them with 20 percent smaller houses to expand outdoor space for their primary property.
But the Palo Alto Architectural Review Board denied his request in part because the houses were not “credible” single-family homes.
1400 acres of Hawaii land
Mark also owns a whopping 1,400 acres of Hawaii land – which is worth a whopping $116 million (£84.2m).
The land, spanning most of Pila’a beach and Kahu’aina Plantation, includes a 6,100-square-foot house with a 16-car garage, offices and part of Mark’s $23 million (£16.7m) security team’s headquarters.
According to local paper, the Garden Island, Mark faced national outrage in 2017, when he filed quiet-title lawsuits to buy pockets of land – called kuleana parcels – within his estate.
These landlocked patches of land were granted to native Hawaiian tenant farmers in 1850 and handed down through generations.
Mark withdrew the lawsuits after public backlash, but he still spent another $45.3 million (£32.9m) on 89 acres spanning at least 12 kuleana parcels.
And in March this year, he bought another 600 acres of land for $53 million (£38.5m).
£42.8m Lake Tahoe holiday homes
In 2018, Mark spent $59 million (£42.8m) on two Lake Tahoe homes — the Brushwood and Carousel estates, which span almost 10 acres together.
The Brushwood estate has a six-bedroom, five-bathroom home, with approximately 400 feet of lakefront, a private pier, patios, a guest house and a garage.
It had previously been used to host the Oscar de la Renta fashion show and the Lake Tahoe summer music festival.
Meanwhile, the Carousel estate has eight bedrooms and nine bathrooms.
On top of that, it has 200ft of lakefront, a marina-style pier and a two-car garage, plus a guesthouse and a caretaker’s apartment.
$400 grey t-shirts
While his homes are very luxurious, Mark’s style is very simple.
Most days, he’ll be wearing a grey t-shirt, a hoodie, a pair of jeans and some Nike trainers.
Speaking about his uniform, he said: “I really want to clear my life to make it so that I have to make as few decisions as possible about anything except how to best serve this community.”
But while his iconic t-shirts are just plain grey, they’re not cheap.
Made by Italian designer Brunello Cucinelli, the tees cost $300 to $400 (£220-290).
£1m sports car
Mark usually has quite inexpensive taste in cars, and has reportedly driven a $30,000 (£21.8k) Acura TSX and a Volkswagen Golf GTI for years.
However, in 2014, he splashed out on a Pagani Huayra supercar for $1.4 million (£1m).
Pals with Vin Diesel
But one of his more unlikely friendships is with Fast and Furious actor Vin Diesel.
The pair became friends when they presented an awards show in 2017.
In 2017, Vin told the New York Times: “I love him. He’s such a great guy and he’s a fan of my work.
“It’s at a point where if Mark and I are together and if I quote a line from a character I played and I do it slightly wrong, he’ll correct me. It’s embarrassing!”
