Thanks for a thread which is refreshingly cerebral without the usual ET combative tone.
Hopefully, with respect to the OP(第一個PO文的人), I will admit that I have strong opinions based on years of trading and study. Surprisingly, a study of Game Theory and Gambling is what led to my becoming proficient at Day Trading.
Systematic application of rules that "must work", due to statistical certainty, is key -- along with practice until rules become habitual. Conclusion: DayTrading may be consistently profitable and while difficult is is not impossible. The best background tor success is mastery of heads-up poker, as opposed to tournament poker, chess (timed), and bridge masters. Holding a Black Belt Karate designation may be a plus. Proper health and meditation practice are also important to consistency.