Actually you are wrong, the war did a lot to help the economy. Most people do not realize that before Pearl Harbor there was a mass mobilization underway. The British bankrupted themselves buying weapons from the US before the 1941 lend lease act.
All the money they poured into American armaments manufacturers started putting people back to work and got the American industrial base onto a war footing before Pearl Harbor. That is an important historical fact that most people are totally ignorant of. It took 18 months for American industry to mobilize for world war 2. That 18 month mobilization was begun by the British buying arms in 1940. A lot of Americans think that right after Pearl Harbor we were suddenly producing massive amounts of weapons because the US can do anything, but that is not true and people have unrealistic ideas about America because of it.
For example there was the naval expansion act of 1938 followed by the much bigger naval expansion act of 1940 then the second naval expansion act of 1940. Most people do not realize that all the new aircraft carriers and battleships that fought in world war two were already being built at the time of Pearl Harbor. In fact a good number of those ships hulls were already in the water being fitted out when Pearl Harbor was hit.
The American economy was starting to pick up at the time of Pearl Harbor and the US was only at war for four years. The 330,000 dead was a terrible loss of life, but it didn't cost much. During that time a lot of consumer goods like automobiles were not being made or rationed. Because of that at the end of the war there was a huge pent up demand from a populace that had money to spend.
During the war there was a massive expansion of the industrial base and none of it was damaged. There were 14 million men in uniform getting food, housing and a paycheck. There were millions of armaments workers making good money and not having much to spend it on, so there was a lot of savings. There had been revolutionary advances made in technology.
There were a lot of people who had received advanced technical training in the military. ie after the war there were thousands of trained pilots, aircraft mechanics. That combined with new paved runways, bigger, better, faster airplanes ushered in a new era in air travel.
As tragic as the war was it worked out well for the US.