Traders naturally like to buy weakness and sell strength. This behaviour is probably worse than random entry.
Coupled with riding losers and cutting winners this is all deadly.
Also traders naturally like to add to losers instead of adding to winners. So winners are small and losers are big.
Do not under estimate commissions for active day traders, 20 trades a day = 5000 trades a year, that alone could be 50% of the account gone to your broker within six months.
Also cannot under estimate bid/ask spread for some types of day traders
Even a 1tick spread is large if you are aiming for say 20 tick stop with a 20 tick target.
Trade is no longer 50:50 bet when a spread is involved.
Then you also have skid/slippage on fills in fast markets.
And i forget to mention leverage, a day trader can use margin 4:1 in stocks and 40:1 in futures and fx, to destroy the account pretty quick.