The British did colonize more places. Places like Malaysia, India, etc., that aren't as prosperous and developed as Hong Kong and Singapore. Much of Britain itself isn't as prosperous and developed as Hong Kong and Singapore. Obviously it wasn't a case of the British simply building HK and Singapore. Singapore wasn't a very prosperous and developed place when the British left in the early 60s. It became so subsequently under local elites like Lee Kuan Yew. Hong Kong and Singapore were built by its locals, who were mostly Chinese but also included Indians, Malays, and others.