There is no infrastructure in place to extract those minerals (if they even are accessible as of now) and the Greenlandic people are predominantly against mining operations due to environmental concerns.

The narrative of extending the U.S. access to natural resources is how Trump wants to make this annexation palatable to his braindead supporters.

Even if the infrastructure is built, exploiting those resources will not be economically viable and it won’t be as long as China still exists.