Even if you make war cheaper countries will spend their full vault to win.
The price of war is always equal to what you have to spend (if its a war of attrition) unless you lose so badly that you can't fight back anyway
Discussion
When the vault is empty we'll make war bonds. When that doesn't work, slavery.
Don't give up, we'll make it work.
Drones and robots will help. It's ok.
Governments will have to rely on bonds a lot if they want to survive hyperbitcoinization. Bonds and taxes are going to be the two main ways to fund both necessary public goods and also frivolous government spending such as wars.
But taxes are going to get quite harder to levy if the government doesn't know how much money everyone has. So the only remaining viable option is bonds. Except now the government has the potential to trap itself in its own debt the way people get trapped in student loans and other debts in US right now. That would be rather amusing to watch, especially if it happens to US.
Then, some more savage failed states might turn to attempting to enslave people by force. My prediction is that it'll seem to work until it stops working — either there will be no more slaves because everyone runs away or goes into hiding, or because people will die so much the country will empty itself. (I wonder if any countries today are in danger of a similar scenario unfolding ✨ y'know what I mean)
>When that doesn't work, slavery
They usually call it "conscription" but you get the idea