First, the vast majority of the locals hated the protests and didn't support them. This isn't reported by the western media. The media reported it as all HK people were being wronged.
Second, most of the protests were done by young people who lost hope in Hong Kong's ultra expensive housing and ultra stressful life. They live in tiny studio sized apartments with the entire family. Buying a home was out of reach for most young HK people unless they have financial help from parents. This was a key trigger in why the youth were protesting.[0][1][2] Again, this was never reported or mentioned by western media. Zoom out 10,000ft and the HK protests and Occupy Wallstreet protests aren't really all that different. Young people felt hopeless economically.
Third, Joshua Wong went to foreign governments and invited them to help him against China. Hong Kong belongs to China if you forgot. This is considered treason in just about any country. Imagine if BLM protestors physically went to China's CIA equivalent to ask them for help against the US government.
[0]https://johnmenadue.com/post/2021/04/hong-kongs-housing-cris...
[1]https://www.aljazeera.com/economy/2019/8/11/a-lack-of-afford...
[2]https://onlinelibrary.wiley.com/doi/full/10.1002/ejsp.70001