She was only eight when she began visiting the family’s bank during school holidays. Today, Suzan Sabanci Dincer is its managing director and will one day take over an empire employing thousands of people in dozens of companies all over the world.

Meet the billionaires of the Bosphorus. Technically, Sabanci Dincer, 42, does not make it into this exclusive club at the crossroads of Europe and Asia. She is, after all, worth only $950m.

It is only a matter of time, however, before she joins several other members of her family on the Forbes list of billionaires.

Once known for its shanty towns and sardine fishermen, Istanbul has emerged as one of the world’s richest cities, home to the fourth highest number of billionaires, behind Moscow, New York and London.

Extraordinary wealth may not always be what springs to mind in connection with Turkey. Just north of the border with Syria are settlements where people still live in conical mud huts that seem to date back to the dawn of history.

Yet according to figures published by Forbes magazine last week, the opulent villas and wooden waterfront mansions lining the Bosphorus – Sabanci Dincer lives in one with her husband Haluk and two children – are home to 35 billionaires, up from 25 in 2007.

Sebanci Dincer remembers learning the ropes of banking from the former chief executive of Akbank, the family concern she now runs.

“He would tell me that a good banker has to know very good mathematics and would give me all these maths questions,” she recalled. “I’d carry his files and do the homework he gave me and he’d reward me with chocolates.”

She was evidently a good pupil: she is being groomed to succeed her father Erol, 69, when he retires. She must also have listened to her uncle, Sakip Sabanci, who built the second largest conglomerate in Turkey and once explained the secret of becoming extremely wealthy thus: “Having help from God, then luck and then you have to work really hard.”

The number of Turkish billionaires is a testament to a remarkable change only seven years after a currency meltdown left the country’s economy teetering on the point of collapse. Istanbul is again enjoying the commercial importance that made it the centre of empires for centuries.

A capitalist boom in recent years has attracted a flood of foreign investment. Property prices have doubled, and in some areas tripled, in dollar terms over the past five years.

Glitzy shopping malls selling luxury goods have proliferated. The business district has been transformed by shiny new skyscrapers.

The new-found wealth has yet to trickle down to the mass of the population. For most of Istanbul’s 14m inhabitants, simply making ends meet remains a constant struggle. Yet there is little sign of resentment at the huge fortunes being accumulated along the Bosphorus, the waterway that winds through the heart of the city. Instead, the wealth has turned Istanbul into a city of dreams.

Most of those on the Forbes list belong to just a handful of families, such as the Sabancis, who have made their fortunes over the past 50 years in industry, banking and construction. Good political connections have helped them to flourish.

The Koc family has enjoyed such a close relationship with the state that at one time its various companies employed more than 100 retired military officers to facilitate relationships with the otherwise onerous state bureaucracy.

Ahmet Calik, one of the newest members of the Bosphorus billionaires’ club with a personal fortune of about $1.5 billion, is a close friend of Tayyip Erdogan, the prime minister who came to power in 2002.

Last year Calik appointed Berat Albayrak, the prime minister’s 26-year-old son-in-law, as his company’s general manager. It is possibly no coincidence that the company has recently secured a number of lucrative state contracts and privatisation deals.

Aydin Dogan, a Turkish media mogul whose wife and four daughters are all included on the billionaires’ list, is always treated with considerable caution by the political party in power.

Other billionaires were following the example of the American Bill Gates, founder of Microsoft, and using their money to bolster their standing. Husnu Ozyegin, whose $4 billion makes him the third richest man in Turkey, has spent $50m of his own money on building 36 primary schools.

There have been occasional reminders that wealth does not necessarily bring happiness. Ali Nuri Colakoglu, the brother of Hasan Colakoglu, 26th on the Forbes list, shot himself in January on the shores of the Bosphorus and died.

Billionaire cities

1 Moscow, 74 billionaires, average net worth $5.9bn
2 New York, 71, $3.3bn
3 London, 36, $4.1bn
4 Istanbul, 34, $1.7bn
5 Hong Kong, 30, $5bn
6 Los Angeles, 24, $3bn
7 Mumbai, 20, $7.6bn
8 San Francisco, 19, $3.1bn
9 Dallas, 15, $2.6bn
10 Tokyo, 15, $2.8bn
Source: Forbes

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