Many justify a long-term, sometimes subtle (even vague) concept that has been codified through years of education, culture, propaganda, and tangible massive on-the-ground benefits. That concept and the reason people on the east coast (Hans) support exploiting, manipulating, and projecting power on the west (Tibet, Xinjiang, Inner Mongolia, etc.) is determined by geopolitics. In one case, China's water resources and long-term economic stability depend on controlling the highlands in the west. The rest is just fabricated reasoning sugarcoating their strategy to cover this strategic vulnerability. A typical Han Chinese with roots in the developed east might not think in these terms transparently. Still, it has years of education and the harsh reality of its region to transform this into an assortment of (un)justified reasoning. They need it to control and secure their stability.
This has also been the case in many other regions, for example, the Middle East, where such harsh geopolitical realities have been codified in different nationalistic and sectarian fractions.