On the other hand, remember World War 2 and the Great Depression.
The pre-war build up? That had a nice side effect of boosting the economy. The actual war, however, everything from coal to clothes to food, was hugely expensive and rationed. Every male between the ages of 18-30 was conscripted and all savings went into war bonds. People were really living it up back then.
I'm not saying to bring back the draft. The buildup helped, though, and I'd actually like to see the option for people to buy war bonds to come back.
The point is that living in a war economy fucking sucks. Not only is supporting a huge war like that is a massive drain, but also said war becomes #1 priority while the citizens' needs come second. That's why rationing becomes a thing.
Then of course there's the government, and the astronomical amount of debt it would have to wrack up to pay for such a massive war. Like I said, it would turn the entire 1st world into Greece within a week.