Well...
Rome was built on the spoils of war.
WWII brought the US out of the depression and the infrastructure we built brought about the biggest boom in our history. I am not sure how the accounting works for us and the war cost to the ROW was horrendous. We were lucky to come out unscathed from a capital stand point but the loss of lives can't be measured. We lost at least one dead certain president and who can calculate the value of the thousands of fallen.
No spoils anymore, the cost of war is prohibitive. The cost of a defensive posture brought down a major world power and and it is damn near squeezing us dry.