It looks huge on a Mercator Projection map even though it isn’t that large.
In the Mercator projection it appears to have about the same area as Africa, while in reality it is about a 14th of it. But, I wouldn't say that "isn't that large": if Greenland was independent it would be (and Denmark is, because of it) the 12th largest country in the world.
I just realized that you posted this comment the day before Trump told Trudeau that Canada should become a US state 👀
(Unless I'm missing something I don't think the idea had been discussed recently prior to that...)