CPEC is to aid development of not only Pakistan but the whole of Western China
China has a problem it us a nation of two halves with the Eastern side the hub of its manufacturing and population, it wants to shift both population and industry to its western half to develop that also,
It has a problem however, the western half is in competition with is eastern half, why would manufacturers go to western China with less developed states, less people and expertise, higher transport costs and facilities etc etc
Eastern half of China has a coastline. Western China has none. There is a reason most of the world population lives in proximity to coastal areas