I'm not a great fan of Trump, but you do need to understand a little bit of reality.
For decades the US has protected Europe by massively overpaying on the NATO deterrent, while Europe neglected to play their part by investing proportionally similar levels of funding. Hence Europe has piggy backed off US defence spending for decades. And whilst European economies seem determined to cripple themselves and de-industrialise by throwing the kitchen sink at economically ruinous Net-Zero, Europe is as a result, fast becoming an irrelevance on the global stage. Here in the UK, the Chinese are in the process of taking over our motor industry (among many others), and we can't even defend our countries borders any more, let alone protect places like Greenland, Ukraine, etc.
In the meantime, the Chinese economy has risen to such an extent, such that there are now two major power centres in the world, the US and China. China currently control 85% of the global supply of rare earth metals and other raw materials needed for AI, data centres, electric vehicles, etc, etc. China has eyes on Greenland as a strategic source of resources. For our own economic security (what we have left of it), the US and the West can't let that happen, but Denmark and Europe can't protect Greenland from the Chinese threat given the dire state of our armed forces. Only the US can guarantee the security of Greenland going forward.
Donald Trump seems to be the only politician of note to be telling it as it is, and yes it's a shame he goes about things like a bull in a china shop, but that's his way of negotiating. He gets so much push back and negative press because long-established vested interests (who own and control mush of the media) don't want to change their cosy ways of doing business. But he's mostly right though.