Let's talk about another simple sentence: profit and loss come from the same source. The surface meaning is simple, and many people have explained it or even experienced it firsthand. Investment/speculation/gambling, no matter what kind of betting you are making, are essentially following a certain system. Of course, you could say that I just follow my feelings and buy/go long when I see an increase, and sell/go short when I feel a decrease. This can also be considered as some kind of system, but the win rate/odds are generally negative overall. Every mature market participant, to some extent, will have their own system. This determines the investment decision-making method, which market to participate in, position control strategy, take profit and stop loss, etc. This series of behavioral patterns, combined with rational/emotional judgments on these patterns, will ultimately form a systematic ev. Why do some people, you see them making big profits and then making outrageous mistakes, just because 'profit and loss come from the same source'. In his system, he will implement a certain strategy based on certain situations, but the market is changing, so you may think he is sometimes a "god" and sometimes a "counter pointer". Why do you think the same gameplay as others, where he makes money and you lose money? It's simple, even if the gameplay looks the same and the system is similar, if he is just slightly stronger than you in terms of experience judgment, assuming he can achieve a 51% win rate and you are 49%, then in the long run, he is a positive ev and you are a negative ev. Profit and loss come from the same source, which is a result. The process is the process in which each market participant strives to adapt to the market version, constantly forming and refining their own system. If someone says they can make money under any market conditions, you can simply conclude that they are a fraud. There is no system that can adapt to all market environments. What we can do is to optimize and improve our system based on our own characteristics, reduce losses, and increase profits. It's just so plain and unadorned, without miracles or skilled hands.