I think in reality the UK (& Netherlands) gave up up enormous amounts of territory after 1945. Did the HKG residents get an fair vote in recognition of their right to self-determination under international law? Maybe sent some ships to scare the Chinese?
Falkland Islands 3.000 inhabitants, Hong Kong: 6.000.000+. Economic value and history; why even compare.. turned over to the Chinese 15 yrs after the Falklands..
Of course we should protect the rights of people. And does the amount of people involved really matter in keeping up those rights? Well, yes actually.
We don't want (more) small minorities setting the world on fire everywhere. It's irresponsible.