Science fiction rarely is about scientists doing real science, in its slowness, its vagueness, the sort of tedious quality of getting out there and digging amongst rocks and then trying to convince people that what you're seeing justifies the conclusions you're making.
You can never properly predict the future as it really turns out. So you are doing something a little different when you write science fiction. You are trying to take a different perspective on now.
You can only kill disappointment with a new try.
Economics was like psychology, a pseudoscience trying to hide that fact with intense theoretical hyperelaboration. And gross domestic product was one of those unfortunate measurement concepts, like inches or the British thermal unit, that ought to have been retired long before.