The Hongkongers have everything to lose, not nothing to lose as proclaimed by the protestors.

https://sg.finance.yahoo.com/news/now-never-hong-kong-protesters-230324090.html

The Hongkongers don't really know what they're doing and also the repercussions they'll face in the future.

HK will become a sunset city soon because of the latest economic measures in Shenzhen.

http://sg-stock.blogspot.com/2019/08/hong-kong-is-being-marginalized-by-china.html

They claimed that the housing cost was too high in HK but it was the HK residents (landlords) that blocked the revamp of the housing policy especially the land sales.

Tung Chee Hwa (ex-chief executive of HK) tried to resolve the housing problem by releasing more lands but he was forced to step down after facing severe protests against it because the land sales would bring down the property prices and rentals.  Thereafter, nobody is willing to revamp the housing policy for fear of the same backlash.