It's not just 1 old man. Most of the wars Trump does is just a logical continuation of the military industrial complex strategy, he just doesn't hide it at all.
Venezuela was already a target, Panama was already conquered, and I'm sure Greenland was in plans already.
The US already has 1) a base in Greenland, and 2) and agreement with Denmark that they can arbitrarily increase their presence there. America could increase it's presence a hundredfold and start putting missiles there, and Denmark would be fine with it.
America is threatening Greenland for one reason: Trump wants to brag that he added Greenland to America.
Venezuela has been an issue for all administrations since Bush. Greenland has never been an issue because there is absolutely no rationale for it. The US can put as many troops there as it likes and is welcome to try to profitably extract minerals from a frozen wasteland. This is just Trump wanting legacy because he’s a narcissist.
Venezuela was already a target, Panama was already conquered, and I'm sure Greenland was in plans already.