You said ...... " ..... investors- who know how to do math better than economists.... " ..... I've worked in both finance and economics and do not agree one field requires more math than the other.
Economic forecasters must make assumptions to estimate the economic future. So, selection of assumptions is key. If the assumptions are biased, then ultimately the forecast will be biased.
Economists must by objective. Otherwise, they become biased. Perhaps, Erza Klein is an example.