Silicon Valley created 23 new billionaires last year, including the founders of Uber, Airbnb and Snapchat, as the global elite increased its total wealth to $7tn.

A total of 290 people were coined dollar billionaires in 2014, taking the number of global billionaires to a record 1,826, according to Forbes magazine’s annual rich list, published on Monday.

Collectively, the billionaires saw their wealth increase by $650bn to $7tn – more than the gross domestic product of Germany and the United Kingdom combined. Most of the 290 new entrants on the list come from China, which produced 71 new billionaires last year.

The international poverty eradication charity Oxfam said the rate at which a “very few at the top are coining it in” was a “moral outrage” when more than a billion people were going to bed hungry every night.

A lot of the fresh fortunes were coined in Silicon Valley. Garrett Camp, 36, and Travis Kalanick, 38, the co-founders of controversial taxi app Uber, joined the list with estimated fortunes of $5.3bn, making them the joint-283rd-richest people in the world.

Uber’s first employee, Ryan Graves, who is now the company’s head of global operations, has an estimated fortune of $1.4bn from his stake in the company, which was recently valued at $41bn.

Graves, 31, got his job at Uber after he tweeted “hire me :)” at Kalanick in January 2010, when the latter was in the process of setting up the company that would become Uber.

“Funny story how we brought him in,” Kalanick said, of hiring Graves. “I was hitting Craigslist, Twitter, and other channels looking for the right candidate. What resulted was the Awesomest job post and response I’ve ever seen.”

The trio who created Airbnb – Brian Chesky, Nathan Blecharczyk and Joe Gebbia – also joined the Forbes list with estimated fortunes of $1.9bn.

Airbnb, founded in 2008, is reportedly close to achieve a new funding drive that would value the company at $20bn – more than twice the market capitalisation of InterContinental hotels.

The youngest new billionaire also made his money in Silicon Valley. Evan Spiegel, the 24-year-old co-founder and chief executive of photo-sharing app Snapchat, is worth $1.5bn. His co-founder Bobby Murphy, 26, also has a $1.5bn fortune.

Perhaps the most famous new billionaire is basketball star Michael Jordan. He joined Forbes’s 29th annual list with an estimated $1bn fortune. The Nike Jordan brand grossed an estimated $2.25bn in 2013, earning Jordan about $90m. His majority stake in the NBA’s Charlotte Hornets is valued at an estimated $500m.

From China Jack Ma, founder of Alibaba, the e-commerce site that floated last year and is now valued at $210bn, is ranked as the world’s 33rd-richest person with a $22bn fortune.

The US turned out 57 new billionaires, followed by India with 28 and Germany with 23. There are a record 46 billionaires under 40, with Facebook founder Mark Zuckerberg, 30, moving up five places to 16th with $35bn.

The Microsoft founder Bill Gates was declared the world’s richest man for the second year running, with a $79bn fortune, up $3bn on the previous year. He beat the Mexican business magnate Carlos Slim, who had a $77bn net worth. Warren Buffett was third with $73bn.

Most of the biggest losers were Russian. The number of Russian billionaires dropped to 88 from 111 last year, putting Russia behind the US, China, Germany and India.

Nick Bryer, of Oxfam, said the Forbes list was “yet more evidence that the very few at the top are coining it in”.

“At the other end of the scale there are nearly a billion people who go to bed hungry every night,” he said. “Such extreme inequality should concern us all, not only because it is a moral outrage, but because it is undermining growth and creating one of the most significant barriers to ending poverty.

“Economic growth does not inevitably trickle down to help those at the bottom. Money can be used to buy power and rig rules, regulations and policies, creating this huge void between the rich and poor and between those who can and cannot access opportunities.”

Bryer called for a fairer global tax system, one that “clamps down on tax dodging by corporations and rich individuals, [and] would help to close this gap and tackle the growing problem of inequality”.