Remember, Trump likes deals. I’m certain that he can offer the Greenlanders enough that they’d sign on.
Why Denmark thinks they should have the authority to veto such a deal, against the wishes of the Greenlanders, I don’t know.
Denmark cannot politically prevent Greenland’s independence if a clear majority of Greenlanders demand it as under the 2009 Greenland Self-Government Act, there is a formal legal process for changing Greenland’s status - referendum and then negotiating the terms of separation.
Danish Prime Minister Mette Frederiksen has repeatedly stated that Greenland’s fate is for Greenlanders to decide, and it is “almost impossible” for Denmark to block a democratic move toward independence (or merging into the USA).
Denmark has no authority to “sell” or transfer Greenland to the U.S. without the consent of the Greenlandic people.
If Greenlanders voted specifically to join the U.S., Denmark cannot say anything legally under the agreements they themselves have signed.
If Trump offers the Greenlanders universal healthcare, their Inuit language as the only state language and also representation in Congress and the Senate, then they would join i think
For the same reason Lincoln thought the CSA had no right to secede?