It's certainly a dream. It would require some type of worldwide disarmament agreement since any power that had a military could ostensibly bully the ones that did not (and just take what they wanted).

800bn just for the US, that is

More than everybody else combined.

Not that we get that much for the money: probably most of it is simple (wholly-legal!) graft, as with NASA's SLS rocket.

What we get for the money is a whole lot of aggressive expansionist wars, all over the world, that never happen. Unfortunately some still manage to slip through the net, like the Iraqi invasion of Kuwait, and the Russian invasion of Ukraine, but if the west generally didn't spend a whole ton on military preparation I believe we'd see an awful lot more of those sorts of conflicts everywhere. Here's a historical graph of deaths from warfare.

https://www.vox.com/2015/6/23/8832311/war-casualties-600-yea...

You can see that after the collapse of the Soviet Union, deaths per population from warfare dropped off a cliff. Unfortunately deterrence is hard to quantify because it's about making things not happen.

Unfortunately, the spending also provided a huge military comfortably capable of over-responses and misdirection in the context of small but dramatic threats.

A vast amount of US "defense" spending since 9/11 has been a "war on money" in the form of massive unending offensive plays against countries that had/have undesirable aspects, but that didn't declare war on the US.

We also get all sorts of aggressive wars and foreign interventions from the US and its allies. Iraq, Libya and Yemen come to mind.

When what you have is a hammer... but that isn't an argument for not having a hammer in your toolbox.