This is something I don't understand as well. Why didn't Hong Kong choose to become an independent state when they had the chance? They could have thrived like Singapore does.
In Hong Kong one can go for protest if its not breaking the National Security Law, in Singapore no one can protest unless approved by Police, recent case highlights it when a student send a tweet to protest when Australian Prime Minister Scott Morrison visited Singapore [3].
Hong Kong is still very good when it comes to internet and freedom of expression. Also it follows common law jurisdictions and judges are able to give judgements against the government in many instances. Also Singapore has POFMA [4], which is worse than rules in Hong Kong.
In Hong Kong anyone can form a company and manage it without having a local permanent resident or citizen as Director. In Singapore one cannot form a limited liability company easily unless has a local permanent resident or citizen as Director (for others need a special conditions and permission).
[1] https://freedomhouse.org/country/hong-kong/freedom-world/202...
[2] https://freedomhouse.org/country/singapore/freedom-world/202...
[3] https://www.channelnewsasia.com/news/singapore/spf-tweet-pro...
[4] https://en.wikipedia.org/wiki/Protection_from_Online_Falseho...