It is a political question and therefore impossible to not awnser political
Trump wants to create a country in which the wealth of the nation is neither dependent on imports from other countries nor on the skilled workers within the nation
Why would you want that? Because setting up a more authoritarian government, where the government tells you what values, religions, and sexual orientation are acceptable is easier if neither your people nor other more liberal countries can stop you.
How would you achieve that? See Russia, have little complex labor and more simple or automated production. And rely on natural resources like gas and oil. Annex countries that have oil and gas but no strong military. I would assume both Canada and Greenland have gas reservoirs that are not used out if fears for environmental drawbacks. Trump could than use the fas without having to deal with disasters in his original borders
Assuming Trump acts logical, this annexation would help his goal while the negative relationships would not affect him strongly after he achieved it.
Or he just wants it because they said no, and he doesn’t realize how much global relationships affect even countries that would prefer to ignore them
I did not steal this meme. We assimilated it.