Like what? After a war everything is bombed, destroyed or polluted. Iraq didnt even have running water. Economy was in ruins. Its not the dark ages any more, microchips are more valuable than gold and even oil needs serious infrastructure.
Every war is extremely expensive - for the amount if money spent in iraq US could have bought every homeless person a penthouse. On the moon.
Shelling nuclear power plants, for example [1].
The expensive part of modern warfare is precision. Abandon one's soul, dial up the yield and razing a nation becomes quick work. Ancient armies wiped out civilizations with less firepower than a CVN. They were simply unconcerned with being brutal.
[1] https://www.reuters.com/markets/europe/top-wrap-1-europes-la...