(Another fun fact is defense companies make fewer profits during war, not more. Presumably because they have to make real products instead of designing imaginary ones.)
The main way the US, UK, and the Netherlands historically became rich was through maritime trade. Maritime trade was basically only possible due to those countries' military expenditures on having strong navies. I know the media makes a big focus on US special forces and other things, but the US Navy is basically the most important and foundational part of all of the US military power. The US and Allies were always interested in maintaining freedom of navigation and trade at the seas.
Just take a look at how much money was lost due to trade shipping costs due to the Houthis in Yemen. Consider that today it's cheaper than ever to ship things, and even today, it was so terrible. Shipping by land is terrible. The only historically economically feasible way to do maritime trade has been with Navies to provide protection from pirates.
Military spending is largely economic dead weight, roughly the equivalent of handouts. And the end result is deterrence in a game of prisoners dilemma. Yet it is sacrosanct, and subject to ever increasing budgets for no gain.