The cost of living on Chongguang Island was much higher than on Happiness Island because Chongguang Island didn't have as high a employment rate as Happiness Island.
This meant that from the beginning, Chongguang Island was populated entirely by elites of varying degrees and levels, with virtually no lower-class civilians. All repetitive, non-creative jobs were taken over by artificial intelligence, which also meant that it was very difficult for ordinary people to find jobs, and they naturally couldn't survive. Those who could escape to other Sky Islands and were accepted by them were considered lucky.
Similarly, as the number of living people in the market decreased, it also meant an increase in prices. Merchants needed to earn more money from fewer people, and the wealthy didn't care about the slight difference in prices.