Britain screwed Hong Kong, not us. We can't run our own country, OK? We love to pretend we can run stuff.
My thoughts on Hong Kong: Like many other human rights and democracy promotion issues, I am not sure exactly how much the United States, or any person or organization within it, can actually do to change the facts on the ground. They can voice their opinions and even lobby/pressure for changes with incentives (better done with other allied countries, but even that is no guarantee) but ultimately things in other countries, especially one as large as China, are gonna happen according to conditions within that country over which we have little control. Look at Iraq and Afghanistan, the US literally sent troops in to topple the ruling regime and it is at best debatable much of a positive impact resulted.
This is a good point and the truth is the US can't do much to change what's happening on the ground and any attempt to do so will make things worse. The PRC is very sensitive to what they perceive as foreign interference. Even under the Basic Law before the latest security law the PRC could intervene militarily in HK if there was foreign involvement. Any move by the US, UK or any other country in HK will be perceived as foreign interference. Any open move such as aiding HK protesters will likely lead to a blood bath.