Hong Kong,

of Sun Hung Kai Properties, which he cofounded with the Kwok brothers’ father, Kwok Tak-seng, and Fung King-hey, an entrepreneur known as the “king of securities.” Mr. Lee’s two sons, Lee Ka-kit and Lee Kashing, are both vice-chairmen of Henderson Land, handling projects in mainland China and Hong Kong respectively. Mr. Lee has said he is “gradually retiring,” letting his sons take on more responsibility for the business.

The Chinese economy is not just much bigger, it is far more technologically advanced, led by the likes of Alibaba, Baidu and Tencent, whose innovative businesses make the Hong Kong tycoons’ traditional empires look like relics from an earlier era.

The shift in influence has seen Chinese investors buying up some of Hong Kong’s most prominent buildings and most storied assets. Alibaba acquired the South China Morning Post, the city’s main English language newspaper, in 2015. Cosco, the state-owned shipping group, is in the process of taking over Orient Overseas, the shipping company controlled by the family of former Hong Kong leader Tung Chee-hwa, for $6 billion.

While some tycoons worry about Beijing ’s interventions in Hong Kong’s legal system, few are willing to stand up for the territory’s autonomy. When asked at his final press conference in March what he thought of Mr. Xi’s decision to end term limits, allowing him to be leader for life, Mr. Li, who has expressed support for democracy in the past, replied: “If I had a chance to re-elect him, I would have voted for him.”

Anson Chan, who worked with many of the tycoons when she was deputy leader of Hong Kong before and after the handover, argues that this willingness to put profit before principle is as big a threat to the city as the housing crisis.

“At some stage business people here need to ask themselves if they have a bottom line and are they prepared to defend it,” she says. “We have to keep Hong Kong’s unique strengths or it will become marginalized.” — Additional reporting by