Classic brain drain, there should be productivity or value addition to society/economy type factor to multiply with actual number of people left to indicate overall impact on society, My random guess is 2 so impact on society is 200k left (not sure whats latest number on people leaving/left)..
And to make things worse,
https://www.thestandard.com.hk/break...at-7.41m:-dataThe median age of Hongkongers has risen from 31.6 in 1991 to 46.3 in 2021.
there was an obvious declining trend in the city's fertility, with the rate dropping from 1,281 live births per 1,000 woman in 1991 to 772 in 2021.
The median age at first marriage was 32.2 for bridegrooms and 30.6 for brides in 2021, marking an increase of 3.1 and 4.4 respectively comparing with the figures logged in 1991.