So....
Shifting gears today to address some more overtly political things… will get back to the other stuff in the next few days.
Since WW2, the US has acted to keep a lid on Europe. Stationed military forces there, rebuilt their economies, created a new political order, provided them with a nuclear umbrella in the framework of NATO. This was very expensive—but this expense made sense in the context of the Cold War.
With the end of the Cold War and the strategic shift to the Pacific and the War on Terror, the visible rationale for this expense disappeared. The non-visible rational—the one that people do not see and generally do not think about—did not.
What is that rationale? To stop Europe from re-arming and dragging us into another world war, potentially against THEM. It was and still is not in the interest of the United States for the European nations (or the EU) to become a major military power, to match their economic power. Especially with respect to nuclear weapons.
Secondly, to effectively control (with the Europeans) the financial institutions of the world economy which provides a degree of leverage and control and certain advantages to the US and our friends.
The resurgance of a revisionist Russia, with teritorial ambitions and a policy of disrupting the existing order and de-liberalizing both the US and Europe combined with shifts in the political landscape of the western democarcies (the rise of ethno-nationalism and authoritarianism, most blantantly visible in the Trumpist movement in the US) has created a crisis point.
The Trumpist movement has made it very clear that the United States can no longer be relied upon to backstop European security—and that it may, in fact, become a danger to European security.
The seeking of what appears to be an alliance of convenience/despotism between Trump and Putin (and perhaps Xi and Trump, as well) puts an exclamation point on this. Europeans feel threatened and insecure. They are already talking about having to build a future where they do not have to rely upon the United States. Expect further movement in this direction (especially after looking at the results of the latest German election).
We are moving from a relationship of fellow-travelers (if not necessarily the best of friends) to a relationship of adversaries. This is going to have some fairly significant repercussions:
The loss of European basing, logistical support, and direct military support;
The dissolution of NATO in favor of a European military alliance structure, leaving the US out in the cold;
Nuclear proliferation as non-nuclear European powers (notably Germany and likely Poland as France and the UK already have nukes) seek to replace the US nuclear umbrella with one that they control;
Increased European military spending and a rebuilding of potentially adversarial forces that we exercise little or no control over;
Loss of sales of US military equipment to Europe, making US procurement of systems like the F-35 more expensive.
This raises the potential the Europe could go to war either without us or even potentially against us.
Overall, the cost of this in both money and intangibles would be far greater than any savings brought about by an American withdrawal—and would strike a body blow to US national security.
Trumpist attempts to turn US defense arrangements with Europe (or anybody, actually) into what looks like a mafia-like protection racket scheme are very dangerous on a number of levels. Especially when there is no guarantee that we will provide protection, anyway.
Pair these devlopments with what looks like a massive increase in the corruption of the US political and institutional structures and a loss of capability through that corruption and cost-saving measures that largely benefit only the rich and powerful and you are creating a potential powder keg.
Roughly 3% of the world population (by conservative estimate) died in or as a result of the last world war. The war cost over a trillion dollars in the money of the time—and it would be a LOT more now.
Again, the problem is (just like the problem with government in general) that most of this is invisible or not thought of—especially by the people voting.
You do not know what you have until it is gone, and once it is gone it tends to either be very expensive or even impossible to get back.