Why didn't Britain kill all Hong Kong people when it invaded Hong Kong, and then the British immigrated there to live?

1. If occupied and killed, it will only increase the resistance of Hong Kong people, which is not conducive to their own rule; 2. The British occupation of Hong Kong is not an immigrant, but her purpose is to find a transit point and dump goods; Britain prides itself on being a civilized person and doesn't want to intensify too many contradictions. Moreover, Hong Kong is too far away from the mainland, and stability is the first; 4. Hong Kong's local materials are not very rich, and it relies heavily on the mainland, and it does not want to intensify contradictions and create a dilemma; Hong Kong was not monopolized at once, but gradually occupied by wars and unequal treaties. At that time, British colonies were all over the world and there was no need for Hong Kong immigrants.