In the trading market, people always like to discuss prices, but rarely discuss "value." The most expensive thing in the world is cognition; the cheapest is emotion.

Why is cognition the most expensive? Because it determines your position in the market. Two investors face the same stock, the same K-line chart, the same financial report—one sees risk, the other sees opportunity; one panics and sells at a loss, the other buys more at a low. The market hasn’t changed; what changes is the ability to understand it. What’s truly expensive isn’t the stock price but the ability to recognize trends, understand cycles, and identify bubbles and value. This ability can’t be rushed; it requires long-term learning, real losses, post-mortem corrections, and even a few major drawdowns to develop. Many are willing to overpay by 10% for a stock but won’t spend time improving their judgment—yet the market ultimately rewards only the latter.

Emotion, on the other hand, is the cheapest thing in the market. Panic, greed, anxiety, and impulsiveness are abundant in every market fluctuation, almost inexhaustible. Everyone is optimistic when prices rise and pessimistic when they fall. These emotions cost nothing and require no training; they arise naturally. But precisely because they’re cheap, they often lead to the most expensive consequences. Chasing highs, panic selling, and overtrading may seem like operational mistakes, but they’re fundamentally decisions driven by emotion. The market never lacks information; what’s lacking are people who maintain discipline amid emotional turbulence.

If life is treated as a long-term investment portfolio, then improving cognition is the process of continuously adding "core assets," while controlling emotions reduces portfolio volatility. Many focus on finding the next soaring stock but overlook the more important task—building a stable investment framework. Those who achieve long-term, stable profits aren’t always right; they simply have a system that allows them to survive mistakes: position management, stop-loss rules, cycle judgment, and asset diversification. These seemingly ordinary principles are, in fact, manifestations of cognition.

So, if we must price the most expensive and cheapest things in the world, I’d answer in trader’s terms: The most expensive is cognition that can navigate cycles—it takes time, experience, and countless corrections to develop. The cheapest is rampant emotion—it’s almost free but exacts the heaviest toll.

Truly mature investors do only two things: accumulate expensive cognition over time and use discipline to stay away from cheap emotion.