This is definitely an American point of view. The US is a) a very large country which b) has been growing in power throughout modern history and c) has a cultural aversion to 'empire' (whether they are an empire or not is a different matter, but it seems they don't want to be).
Compare that to many European countries, which are a) very small, b) have lost a lot of power in the last 200 years and c) have a (admittedly not universal) nostalgic streak for the glorious days of empire, when they were world powers.
For Americans to sympathise, imagine if in 2100 various states have seceded and the US has split into multiple nations, with the remnant USA consisting only of the New England states. Then Canada offers to buy Maine, which is otherwise a burden on the treasury. Can you see why you wouldn't want to sell?