I have no doubt that there are successful day traders but, there are certain built in disadvantages that make it hard to succeed. Number one is slippage when most day traders trade penny stocks, the number of shares are limited and I imagine the bid and ask spreads are likely to be very wide. Add to that, front running by the day trading gurus. Their students will follow what the say if they say, ABC company is going to skyrocket tomorrow, they are bound to buy it! Of course, the guru has bought it ahead of time guaranteeing that he wins! The followers get hosed, get stuck holding the bag.
I love it when people use the "as a..." as some sort of de-facto proof the plebs reading their post should take what they say as truth. This paper will become a seminal work in economics quickly because it's making so many frauds mad. For a corporate statistician you didn't even do 2 HONEST MINUTES of research. So I did it for you: (b) You're wrong. See the attached photo - The markets for the last ~3 years or better (I only went that far) spent more time correlated than uncorrelated. Before you say "there are drops to negative correlation"! That is still significant correlation. Since this underpins your entire argument (which is a bad argument anyway - correlation is not causation) the rest of your post is invalid. (c) You're wrong again. From (b) and my image linked the markets are highly correlated (|CC(20)| > 0.9 majority of the time). This even makes fundamental sense as we get a lot of softs from Brazil so naturally our economies are intertwined. You seem to have no idea what an actual "representative sample" is (you've even managed to screw up causation by implying market correlation relates to new day trader ability!) Do we throw out health data from Japanese studies because Americans are not Japanese? Are you kidding me "corporate statistician"? Was the auto-maker Saturn?
haa no response for the real bullshit in the study so you focus on whether Brazil market is just like SP500 futures market.... Let's assume they are identical in volatility, volume, breadth and transaction speed, the study's conclusion is still unprofessional and the data set extremely limited. Shit study.
Would be more interested to see a study on experienced traders meeting specific criteria (lets say 4+ years of active trading, adequate trading capital, etc.), Then see what percentage of that group continues to be successful over the following few years. To expect consistent success in trading (or any field) from day 1, or even after 1-3 years, is obviously unrealistic. Cant think of any profession or skill a person can achieve mastery over in 1-3 years. In trading, I would suspect even the few % who Net Profited to be more a product of luck (excellent market conditions for their plan), personal relationships with experienced traders, or some other prior, relevant experience.