Why are back test and paper trading gains often so pristine vs the real life records of many traders / investors?
Prospect theory studies indicate traders / investors are inclined to take small profits but let losses grow in size (gambling, in the hope that money will eventually recover, to at least even) vs letting profits run and cutting losses promptly, and moving on.
Evolved human nature and emotions complicate producing optimal returns in real time vs what is found in back testing and often reported in paper trading.
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