So what you're cynically referring to is the war economy. The caveat of debt to gdp is that it's a balance. If you could take on debt and invest properly to the point that the returned GDP is greater. Then you end up lowering debt to gdp.
The caveat of the war economy is that it's not spent on yourself. The trope as it were is that the USA has been 'nation building' in the middle east and ended up neglecting back home.
For example, I am super excited to learn more about the B21 raider later this year. I expect the cost per stealth bomber will probably be around $5 billion each.
How many schools could you build with $5 billion if they decide to build just 1 less? How many roads could be built if you build 2 less?
My cynicism is more along the lines of
A. Lots of people think GDP == real wealth and can't seem to wrap their heads around our argument
B. You don't have to do better than you have been to keep the global-economic pole position, you just have to be doing better than everyone else. I'm not gonna elaborate on the rest of this, I'll leave that as a sad exercise to the reader.
I really really hope we don't start or find ourselves required to participate in a war.
Nah, us americans are too smart for all that. We'll just start a nice big war.