There's a British psychiatrist on youtube called Dr Russell Razzaque posting some good short videos on Trump. He suggests the issues aren't important for Trump. It's Trump's desperate need for attention that drives him. Trump spouts off to get attention. President Trump doesn't really give a shxt about Greenland. He gives a shxt about the attention. I think this is consistent with Bolton's observations on Trump - Trump is unfit for office and he prioritizes his own personal interests ahead of the US's interests. Trump doesn't care that he has a very limited understanding of international politics.