I recently came across this research paper Day Trading for a Living? by Chague et al. They carried out their study in brazilian stock market.
From the Paper
The paper's conclusion was that it is highly unlikely an individual be profitable if they day trade for a living. Those individuals who was profitable took very risky trades.
From the Paper
We show that it is virtually impossible for an individual to day trade for a living, contrary to what course providers claim. We observe all individuals who began to day trade between 2013 and 2015 in the Brazilian equity futures market, the third in terms of volume in the world, and persisted for at least 300 days: 97% of them lost money, only 0.4% earned more than a bank teller (US$54 per day), and the top individual earned only US$310 per day with great risk (a standard deviation of US$2,560). Additionally, we find no evidence of learning by day trading.