We've all heard Buffett's words: When others are fearful, I am greedy; when others are greedy, I am fearful.

It sounds simple, but very few people truly practice it.
I've also pondered this deeply in trading: when should I be greedy, and when should I be fearful?

The most painful thing is that we often swing between these two extremes.
Sometimes, when a position just shows a little profit, we fear giving it back, hurriedly take profits to lock in gains, only to see the market skyrocket afterward, watching helplessly as we miss out on a big move.
Another time, when there's profit, we want it to run, aiming for more, but then the market reverses, and all the profit is wiped out, leading to regret for being too greedy.

This dilemma is very common in stocks, futures, and forex markets.
You buy at a low, and when the price rises to a profitable level, the market starts to adjust—should you exit or hold?
There are all kinds of voices.
If you exit and the price keeps rising, you blame yourself for being too fearful; if you don’t exit and it keeps falling, you regret not taking profits at the high.
Everyone can be a hindsight expert, but when actually faced with it, the mindset is tense, and rational judgment becomes difficult.

I’ve found that many traders fail because they lack proper psychological control.
They either run at the first sign of trouble or cut losses quickly, or they increase their position against the trend, or blindly chase the market up and sell down, or operate with heavy positions directly.
The first two are driven by fear—afraid of giving back profits, unwilling to admit losses, and even adding to positions with a lucky mindset, ultimately leading to heavier losses.
The latter two are driven by greed—chasing gains when prices go up, selling when they go down, acting impulsively without a plan.

Sometimes, this can indeed lead to lucky wins a few times, but mostly it’s just luck.
In the long run, this approach will inevitably come at a cost.

True experts have a trading system.
They have clear rules for entering, exiting, and managing capital, and they strictly follow them, not losing their composure due to market fluctuations.
Only then can they truly overcome greed and fear.
In essence, the core of Buffett’s phrase—"When others are fearful, I am greedy; when others are greedy, I am fearful"—is not about blindly going against the crowd, but about having a system and discipline.

Interestingly, human society has evolved for thousands of years—from agricultural civilization to the information age—material life has become richer, technology advances daily, but human nature has hardly changed.
However, individuals can evolve.
Those professional traders become winners in the market by continuously practicing and reflecting, overcoming inner fears and greed, ultimately evolving themselves.
Most people, however, cannot conquer their weaknesses in a lifetime.

Since human nature hasn’t changed in thousands of years, we can think differently.
Instead of obsessing over overcoming human nature, it’s better to use analytical tools to understand the general state of market investors, thereby reducing our own risks.
Always respect the market, view market conditions rationally, and within a familiar and controllable scope, continuously improve your trading system.
Only then can you truly understand the meaning of "When others are fearful, I am greedy."