I'm not a trump fan, but the idea is actually not as ridiculous as it might sound. several presidents have looked into buying it before for strategic purposes during the Cold War. (any nuclear attack from Russia could go over Greenland to get to us.) but, right now, Greenland apparently has a lot of rare earth metals, which I think you need for building tech stuff. currently, we're getting them from china. given the trade war, it makes sense to look for another source.