That depends to a great extent on how the money is actually spent. The USA spent huge amounts of money to get out of the Great Depression, much, much more than it was spending before, and it ended up in a much better economic position, despite a gigantic war soon after.

I thought the reason the US ended up with a good economy was because of the war, not despite of it[1]. The war massively ramped up the US's industrial output, and unlike many of the other allied powers there was no need to rebuild once the war ended.

[1] https://eh.net/encyclopedia/the-american-economy-during-worl...

A war doesn't directly improve the economy. It's spending on industry that was justified by the war (plus national fervor) that helped with this. But building ships and planes and tanks is not fundamentally useful for civilian industry. If the same level of investment had been directed to civilian industries instead of military, the economy would probably have been even higher.

I do agree that the relative value of the US economy shot up directly due to the destruction the war brought to European, Chinese, Japanese, and USSR industry and populations - so if you were discussing things in this sense, I can agree.

I really doubt the technology would've advanced as fast without such an adversarial setting. Economic warfare is child's play vs total war.

All that knowledge and redirected output ended up being extremely profitable once it could be used for civilians instead of the military when the war ended.

So, do you know how that magic money should be spent ? And, if you know, do you know how to elect the right people that will spend it on the right things ? There's a high probability it will be spent on friends' big businesses / fraud and abuse