Warren Buffett, chairman and CEO of Berkshire Hathaway
Net worth: $46 billion
Buffett still lives in the Omaha, Nebraska, home he bought for $31,500 more than 50 years ago.
He doesn't own a yacht because, as he puts it, "Most toys are just a pain in the neck." When he married his second wife, rather than a lavish affair, it was a brief afternoon wedding at his daughter's house in Omaha.
He has also given billions of dollars to charitable causes and begged Washington to increase his taxes.
Mark Zuckerberg, founder of Facebook
Net worth: $9.4 billion
As the mastermind behind Facebook, Zuckerberg is a billionaire many times over. But the 28-year-old leads a surprisingly low-key lifestyle.
He recently upgraded to a $7 million house in Palo Alto, but The Los Angeles Times called the home "still well below his means."
Zuckerberg reportedly drives an Acura "because it's safe and not ostentatious," and famously wears the same gray t-shirt and hoodie to work every day.
His wedding to longtime girlfriend Priscilla Chan took place in his backyard, and the pair was seen digging in at a McDonald's on their Italian honeymoon.
Chuck Feeney, co-founder of Duty Free Shoppers Group
Net worth: currently $2 million (he's given away billions)
A Depression-era veteran with a strict personal motto: "I set out to work hard, not get rich."
The co-founder of Duty Free Shoppers has donated more than $4 billion to disadvantaged children and public health initiatives, all while going to great lengths to remain an anonymous donor.
“He has no ego . . . He always chooses the second-cheapest wine from the wine list,” according to his biographer, former Irish Times journalist Conor O’Clery. “When we traveled together he was always dressed like a down-at-heel American tourist.”
Azim Premji, chairman of Wipro Limited
Net worth: $12.2 billion
As the owner of the technology-service giant, Wipro, Premji is worth more than $12 billion.
Regardless, he is said to monitor the number of toilet-paper rolls used in Wipro facilities and demands that employees switch off the lights when leaving their offices.
Premji often takes a three-wheel auto rickshaw from the Bangalore airport when returning from business trips, and drives a 1996 Ford, according to a 2003 Businessweek profile.
"Premji makes Uncle Scrooge look like Santa Claus," said one Bangalore tech executive.
David Cheriton, Stanford professor
Net worth: $1.3 billion
David Cheriton, the Stanford professor who has an estimated net worth of $1.3 billion from Google shares, hates the idea of living like a billionaire.
"I'm actually quite offended by that sort of thing," he told the Edmonton Journal in a 2006 interview. "These people who build houses with 13 bathrooms and so on, there's something wrong with them."
Cheriton called himself "spoiled" for taking a windsurfing vacation in Hawaii, and in a recent Forbes profile said that his biggest recent splurge was his 2012 Honda Odyssey.
Karl Albrecht, co-founder of Aldi
Net worth: $25.4 billion
Aldi is to Europe what Walmart is to the US. Albrecht founded the company with his late brother Theo, and together the two made billions building the notoriously no-frills chain.
Raised by a shopkeeper mom and a miner father, they remained true to the vision of frugality that drove both their stores and their lives. When Theo was kidnapped for 17 days in 1971, his brother negotiated a bargain ransom of $4 million — which he then wrote off as a business expense.
Christy Walton, heir to Walmart fortune
Net worth: $27.9 billion
Walton is the widow of John T. Walton, one of the sons of Walmart founder Sam Walton.
Despite their wealth, Walton wanted a normal upbringing for her son, so she raised him in an 1896 Victorian home in National City, Calif., outside of San Diego.
After her husband died in a plane crash, Walton donated the home to the International Community Foundation – Center for Cross-Border Philanthropy.
Ingvar Kamprad, founder of IKEA
Net worth: $3 billion
The founder of IKEA said he drove 15-year-old Volvo and always flew economy class, according to a 2006 Reuters article.
His frugal ways extend to his home in Switzerland, which is reportedly decorated mostly with inexpensive IKEA furniture, as well as a few family heirlooms.
According to The Daily Mail, Kamprad and his wife are often seen eating in cheap restaurants and haggling over prices at the market.
Note: Some Swedes will tell you that Kamprad is not as frugal as he would have you believe.
Tony Hsieh, CEO of Zappos
Net worth: Close to $1 billion
After selling a company to Microsoft for $265 million, Hsieh could have lived in the lap of luxury.Instead, he has invested $350 million of his own money to transform downtown Las Vegas into a tech hub.
And by all accounts his lifestyle hasn't changed since his early days in business.
"Money is just a way for Tony to get to his endgame," said Erik Moore, an early Zappos investor. "Money just doesn't matter to him. If he only had a million dollars left, he'd spend $999,999 to make Vegas work. He would be just as happy with a dollar in the bank and being around people he cares about and care about him."
Alexander Lebedev, Russian businessman
Net worth: $1.1 billion
Unlike many Russian oligarchs who flaunt their wealth buying apartments, yachts, and jets, Lebedev is notoriously frugal.
From a Guardian profile:
Indeed, the most striking difference between him and other oligarchs is his social activism. Lebedev has used his large fortune to improve the lot of ordinary Russians. He talks enthusiastically about such unfashionable themes as flat-pack housing and potatoes.
He is staunch in his beliefs; Lebedev was charged with "hooliganism" after punching a rival on a talk show last year.
Carlos Slim Helú, chairman and CEO of Telmex
Net worth: $69 billion
Slim may be the wealthiest person on the planet, but that doesn't mean he's an extravagant spender.
The self-made billionaire lives in the same modest six-bedroom house he has owned for the past 30 years, and still drives himself to work, according to The Week.
As far as we can tell, he does not own a yacht or a private plane.
Amancio Ortega, founder of Zara
Net worth: $57.5 billion
2012 was a good year for Zara founder Ortega, whose net worth rose by $22.2 billion last year.
Even so, he hasn't let the success go to his head. Ortega and his wife live in a discreet apartment building in La Coruña, Spain, and he's a simple dresser, wearing a uniform of blue blazer, white shirt and gray pants every day.
He goes to the same coffee shop every day and eats lunch with his employees in the Zara cafeteria. And Ortega drives an Audi A8, not some fancy supercar.
One major indulgence: Ortega owns The Global Express BD-700, a private jet designed by Bombardier that carries price tag of $45 million.
Jim C. Walton, Walmart heir and chair of Arvest Bank
Net worth: $19.2 billion
Walton may belong to one of the wealthiest families in the world, but he has followed in the frugal footsteps of his father, Walmart founder Sam Walton.
The youngest and most private of the Walton siblings, Jim still resides in Bentonville, Ark., where he runs the family's personal wealth management company from the upstairs office of "a plain old brick building" in downtown Bentonville.
In 2007, it was reported that Walton drove a 15-year-old Dodge Dakota.
David Green, founder and CEO of Hobby Lobby
Net worth: $4.5 billion
While he could easily afford a Gulfstream of his own, Green, founder of arts and crafts retail chain Hobby Lobby, prefers to fly coach.
Instead of spending his billions on himself and his family, Green has famously become the largest individual donor to evangelical causes in America. He's given upwards of $500 million in charitable contributions over his lifetime, according to Forbes.
Tim Cook, CEO of Apple
Net worth: unknown, but he made $378 million in 2011
He may not technically be a billionaire, but Apple CEO Tim Cook is compensated handsomely.
Even so, he chooses to live a modest lifestyle. Cook lives in a modest, 2,400-square-foot condo in Palo Alto, which he bought for $1.9 million in 2010.
He's quoted as saying in the book Inside Apple: "I like to be reminded of where I came from, and putting myself in modest surroundings helps me do that. Money is not a motivator for me."
