How do you know these hypothetical people exist? Aside from skill decline with aging and the evolution of the markets the longer a day trader day trades the greater their risk of ruin is by the nature of the concept, unless they are constantly improving their day trading, which is impossible for a discretionary trader trading against evolving algorithms...
That's the key...constantly improving our trading as discretionary traders is
highly possible for us as traders in the age of algorithms. The problem is that most traders are not willing to adapt. Change is an uncomfortable thing to the typical retail trader and ET forum is full of examples of such.
Yet, we all know based on the studies...there are LESS traders today than prior to the 2008 - 2009 financial fiasco...not due to algos. Its due to key changes in volatility that many traders failed to adjust (adapt) that was caused by the 2008 - 2009 fiasco.
The recent China fiasco of August 2015 is just another example of how volatility has a great impact on us retail traders. You can also put the blame on changes in exchange rules since the late 1990s that has impacted traders in a negative way.
Anyway, algos is a problem but not as big of a problem as the above as noted to you earlier when you in prior said its impossible when I made it clear that the small percentage of profitable retail traders are not trying to trade against the algo...not successfully possible. Instead, successful retail traders are following volatility while algo don't want the volatility while they concentrate on competing against other algos.
Its funny because there's a guy here that posted his backtest results (impressive results) and didn't understand the drawdowns of his trade method. It took constant repeating to him by others here for him to overlap a VIX chart with his daily backtest trading results...
He discover his trade method was very sensitive to key changes in volatility. The result was that he doesn't trade every day now. Instead, he only trades when volatility is high or changes dramatically. Thus, he's become more of an efficient trader.
There's many other ways that traders are adapting in the new age of trading WITH (not against) algo city. Hopefully, you don't stay stuck on the "its impossible" thingy and spend your time & energy to adapt. If you're not willing to adapt...stay away from trading and find another career.
Adapt or find another career.