According to Forbes magazine's 2015 edition of the 50 richest people in Hong Kong, there were six men each with a net worth of at least $10 billion. Even though they all found different paths to riches, there are some noteworthy similarities among those in the $10+ billion club. For example, four of these six mega-billionaires were 85 years or older in 2015, with the two remaining both 64.

Additionally, at least three made the majority of their wealth from real estate, which is not surprising given the hyper-expensive Hong Kong market.

1. Li Ka-shing: $33.5 Billion

Li Ka-shing is one of the most important and influential businessmen in Asia. His companies employ an estimated 270,000 people across 52 different countries – not bad for a man who was forced to drop out of high school to support his poverty-stricken family.

Li's family fled to Hong Kong from China during World War II. His father died shortly thereafter, forcing the 16-year-old Li to work in a factory to care for his mother. In 1950, at the age of 22, Li opened his first factory, Cheung Kong, to manufacture plastic flowers.

A self-taught and highly driven man, Li Ka-shing positioned himself in property development to take advantage of Hong Kong's meteoric economic boom between 1975 and 2000. When asked about his keys to success, Li points out that he doesn't "get overly optimistic when the market is good, nor overly pessimistic when the market is down," and that "if you don't have a big heart, you will not succeed."

2. Lee Shau Kee: $24.6 Billion

Another real estate mogul, Lee Shau Kee has earned favorable comparisons to Warren Buffett of Berkshire Hathaway. He is the founder, chairman and managing director of Henderson Land Development Company Ltd., the Hong Kong and China Gas Company Ltd., chairman of Miramar Hotel and Investment, vice chairman of Sun Hung Kai Properties and main sponsor of the Lee Shau Kee School of Creativity.

Famous for his patient, fundamental approach to real estate development and stock picks, Lee is also one of the world's leading philanthropists. He gave away roughly $2 million in October 2015 to celebrate the birth of his seventh grandchild.

3. Cheng Yu-tung: $15 Billion

Cheng Yu-tung built his fortune through a conglomeration of jewelry retail, real estate development and Hong Kong's thriving export markets. Since he is long retired, Cheng's family runs his many business interests, including granddaughter Sonia, whom Forbes names as a rising star.

In addition to his many business titles, Cheng is the honorary representative of the Kingdom of Bhutan in Hong Kong.

4. Raymond Kwok: $14.7 Billion

Raymond Kwok's father Kwok Tak-seng was the original business partner of Li Ka-shing for Sun Hung Kai Properties before giving the family empire to Raymond and his brother Thomas in 1990. Thomas and Raymond were joint owners until 2014, separating from their older brother, Walter, after a long-running feud.

Late in 2014, Thomas Kwok was found guilty of bribing city officials and was sentenced to five years in prison. Raymond was not implicated, and he now works as the sole chairman of the company.

5. Lui Che Woo: $13.4 Billion

Lui Che Woo has a rags-to-riches story almost on par with that of Li Ka-shing. Born in China in 1929, his family fled to Hong Kong when Lui was only 4 years old. He worked at a very early age, selling food and trinkets on the street to help his family.

Lui helped launch a host of businesses, including casinos and property construction companies, between 1950 and 2002. His most famous company, Galaxy Entertainment Group, runs hotels, casinos, resorts and other forms of entertainment.

6. Joseph Lau: $10.9 Billion

Joseph Lau, a 75% owner of Chinese Estates, is currently living in Hong Kong in a form of legal exile. Macau indicted Lau on bribery charges, but Hong Kong does not have an extradition treaty with Macau. Lau was found guilty of paying a Macau public works chief a reported $2.6 million for a land deal. He has since resigned from his chairmanships, but is unlikely to ever serve a day of jail time.