The reason is that the island's residents believe that the standard of living in Denmark is much higher

Snip:

The overwhelming majority of Greenland residents do not want to become US citizens, The Financial Times reported, citing a sociological survey conducted by Verian.

According to the poll, 85% of Greenlanders do not want to become Americans because they believe that the standard of living in Denmark is much higher. In particular, the island’s residents are concerned about crime and expensive medical services in the US.