In 1997 they were British Commonwealth citizens with easier immigration rules than ours. They took the big money and went to Vancouver BC where the price of real estate baca earth out of the reach of normal Canadians.
Canada had (and still has) an immigration system whereby prospective immigrants can buy their way into a permanent residency (like our green card) by pledging to invest a certain amount of money there, $200,000, I think. This is how many HK residents ended up in Vancouver and elsewhere in Canada in the 1990s.
The really rich Hong Kong residents have been moving their money out of HK since 1997, they knew what would eventually happen when China got their foot in the door. A lot of them own property in Australia and much of their money has long been moved to Singapore.