This cartoon is from 70 years ago. 80 years ago was 1943 which was in the middle of World War 2. At that point, war getting a sizable chunk of the GDP was perhaps more understandable. So the caption on the cartoon actually undersells it.
It still made a lot of sense, since you know it was made during the height of the cold ware before ICBMs/mutually assured destruction was a thing, so a ground conflict didn't seem unreal