I guess wanting to buy Greenland is "absurd". According to Trump the Danes lose 700 mil a year subsidizing the island. That money could be used to properly pay the 2% of their GDP for national defense.
1) Greenland is a dependent state, not a distressed asset in a portfolio. They've got their own constitution, their own parliament, their own maritime boundary and they do their own trade deals. Denmark can't just sell off Greenland on a whim - that goes against the constitution of both countries. It's like trying to buy Scotland off the UK - except more absurd because Greenland has more autonomy. Any deal would have to involve Greenland declaring independence. In that regard it reminds me of Gary Johnson (rightly) being laughed out of the room for not knowing about Aleppo. It's fine for you or I to not know these things, but the most powerful politician in the world should be aware of the relevant international law and know what the answer to his offer will be.
2) The subsidy is $535 million. Unless they jacked it up 35% in a year Trump is lying.
https://www.cia.gov/library/publications/the-world-factbook/geos/print_gl.html
3) Their deficit last fiscal year was about $70 million. They're doing fine.
https://www.dst.dk/en/Statistik/emner/nationalregnskab-og-offentlige-finanser/offentlige-finanser To respond to what you're about to say,
4) I actually agree the other NATO powers aren't spending enough on national defence. But there's a huge amount of gaps in logic between not spending enough on defensive capabilities and buying Greenland (should Trump make an offer for French Polynesia because France is also coming up short? And for Denmark why assume they have to sell Greenland and not adjust other forms of spending or add debt while it's historically cheap?). From a US perspective if you're worried about spending too much on the military in the region then just cut back military spending in the region and they can't do a huge amount about it (it's actually a policy discussion going in Europe right now). I said this a few years ago and nothing seems to have been done about it.
5) Public finance isn't the same as corporate finance. If a government posts a loss on (for example) a railway, it's to the gain of taxpayers as consumers. Granted it's a little more complicated than that, but the government recording a loss isn't the same as a company recording a loss. Denmark's not sinking money into an underperforming asset, it's supporting a region that they have cultural, political and historical ties to. Over here we spend a lot more money on the Cook Islands than we'll ever get back, but if a US president made an offer to buy them the PM would quickly tell that president where to stick their offer.
6) As allblackraven said, not everything is about money. There's a reason why the US and Denmark have different rules around resource and environmental protection, for example. This ties back to the previous point that there are cultural and historical ties involved between the two countries (Greenland also has an Indigenous population), and good luck being taken seriously when you put a price on those.
7) Even if you ignore the legal, financial and cultural realities of why that deal is a non-starter (and the fact that no one seems to know whether the offer was serious in the first place should say enough) and you treat it like a freewheeling real estate offer, the other part that made the whole thing mind-blowing is the way Trump reacted to being told his absurd idea is absurd. Cancelling a state visit and calling the PM "nasty" is the most thin-skinned thing I can remember from a politician. I own property and I've received offers and made offers (including lowball ones I didn't expect to stick) and I've never known anyone in the business to react like that to being turned down (even using the word itself, which is far softer than words Trump himself uses on a daily basis). I genuinely find the whole thing staggering and my wife and I have been having a good laugh watching it play out.
