Quite intersting.
From WWI to WWII to the Cold War, you can see expenditure as competition between Great Powers. The UK, France, Germany, Russia, USA, China, etc. It all sort of makes sense as the spending between countries ebbs and flows.
But after the Berlin Wall came down, the USSR collapsed and the Cold War ended, it stopped making much sense. We spend more than ever, and no one else even comes close.
Perhaps we’re doing it wrong.
Especially after 30 years of squandering national treasure in the middle east. That and more than a few folks think China has surpassed the US in military capability except for deployment of power. Hell, we seem to be more interested in social engineering in our services than learning how to steer boats. Maybe there was truth in Eisenhower's military-industrial complex warning back in 1960. America still has the finest soldiers but you do have to wonder about their leadership.
We're not getting enough technological "bang" for our military spending. The military plays an important role as the first customer for "cutting edge" technologies. The biggest app for robotics right now is the battlefield. Instead we're importing millions of low tech third world biorobots to keep our socialist ponzi schemes going a little longer.