The world's economy is such a complicated system that no one can know its state and workings well enough to make any useful predictions. Technological innovation is a major source of uncertainty. So are natural events and disasters (wars, droughts, eruptions, oilfield discoveries, nuclear meltdowns, etc.)
The science of physics is an attempt to understand
All of Reality, which is generally considered to be an even larger set of phenomena than your description of economics

Are you suggesting that since we can never
really understand All of Reality, that no 'hard science' of physics can exist, and that such a purported 'hard science' of physics can't have any predictive power or utility?