One often denied fact is that to be successful in trading, it does not just depend on hard work or perseverance. Most people will never make it no matter how long and hard they try because they simply do not possess the necessary psychological properties required of a successful trader. How long it takes for the few successful ones depends on the individual, the mentor(s), circumstances of the market, capitalization,...
And the study never took any of this into account because it shut off the study period to 1 year only and exlucded all traders with any experience more than 1 year.
So the study is shit.
basic man...