HK and the Mainland are at different stages of economic development with consequent impact on employment and business opportunities. The mainland is a developing economy still not yet reaching its peak. HK already is a developed economy in many respects.
The key is whether China can break the "middle income trap".
A start would be the government making policies for their people. But yes, the problem runs deeper than that since its prevalent in other political arenas as well.
At the heart of it, is that the types of people who get to the top in politics, are a certain type of person. Unless the whole structure of politics i.e. the rewards, the measures of success, the motivations, the status etc. changes, then it will reward the same types of people.
Its like when a person keeps facing the same relationship issues from all their partners. From the outside, its easy to see that they are choosing the same types of people because those types of characteristics appeal to them, without realising the consequences of that type of personality.
Within limits, how else? For example, housing policy favours developers, not the general public.