People didn’t leave for lack of economic opportunities back then. They left because they were scared of the CCP. Same as today, people wanting to leave not because UK has better prospects, but again for political reasons.This is not 1997. China was very far behind in 1997 and you could be very smart and educated but have nowhere to use your talents in China. Today, if you are a talented Chinese, there is nowhere in the world where you could develop better than in China. This is the reality for the rich and educated Chinese today; for different than in 1997. The people who we don't want to leave are those who are talented and would love to contribute to China but would go elsewhere for an easier life/better opportunities. These are not them. Once again, these people hate China and want to be somewhere else; they won't be contributors to China anyway. They'll just be leeches in China serving Western interests.
Let them go. Forcing them to stay is like holding in a dump just to deprive the grass of fertilizer. China has more than enough people and would be much better off if all the hanjian left and we could house patriots in the space they occupied. The UK can take them and be uncomfortable. They don't really want Asians, especially not those who just complain all day, and the Hong Kongers who make it there can feel first hand what it's like to be discriminated against by the ones they held on a pedestal. It's an educational opportunity that there's no place like home.
But I agree, once these HKers settle in the UK, and experience first hand the racism in Europe, they may regret their decisions.
A better destination, from their perspective, is Taiwan.