Major breakthroughs in UK munitions production

And that is even before the observation that killing people isn't necessarily (or even usually) the goal of war.

The British Empire was the drug dealer empire, first with tobacco and later with opium. There were also some spices in there too. But the British Empire at one point covered a quarter of the globe, leading to the double-meaning of "the sun never sets on the British Empire" (also meaning it never ends).

Rome was a little diferent because of simply looting their provinces (by demanding tributes). Instead they formed alliances of mutual benefit and provinces essentially became Romanized. This sustained Rome for ~1500 years (post-Republic, ignoring the Holy Roman Empire).

Spain looted silver from South America.

The USA is an empire but it breaks the mould by generally not using direct colonization. It's probably better described as economic imperialism. Even "global" institutions largely just project US power (eg the IMF and the World Bank).

Ultimately, the US is an arms dealer empire. What backs the US dollar is the US military and, in addition to the ability to directly project global military power, the US has a ton of influence by who it chooses to sell weapons to.

Additionally, there's soft power through things like foreign aid.

Why do I mention all this? Because despite the mantra of "making America great", the current administration is doing more to destroy US direct and soft power than anyone could possibly have imagined, more than current and former adversaries (eg the USSR, China) could ever have dreamed of doing themselves.

Abandoning Ukraine, which is what the US is really doing at this point, may in fact be the catalyst to restart European weapons production. The president may complain that Europe is taking advantage of the US with NATO and we're somehow "paying for European defense" like that's a bad thing. It's not, at least from the perspective of US foreign policy and interests. NATO is what the US uses to control and influence Europe.

If Europe becomes no longer dependant on US weapons and can be responsible for European security, then NATO doesn't really need to exist, which is bad for the US and good for basically everybody else.

Now if the goal is American isolationism then all this sort of makes sense but I don't think that is the goal. Also, it's worth adding that previous periods of American isolationism happened in the lead up to both WW1 and WW2.