One: A Book Full of Bias, But Hits the Mark
'The Crowd' (Psychologie des Foules) is a 1895 work by French social psychologist Gustave Le Bon. It's the foundational text of crowd psychology, hugely influential, but also deeply controversial.
Le Bon's core argument is sharp — an individual alone may be rational, intelligent, and moral. But once he joins a crowd, he undergoes a qualitative change: he loses independent judgment, gets infected by emotion, his intelligence drops, responsibility vanishes, and he becomes impulsive, extreme, and easily manipulated.
Le Bon says — "The individual in a crowd is no longer himself; he has become an automaton without a will of his own."
The book has plenty of outdated and even bigoted content (Le Bon's views on crowds, women, and "inferior races" carry the arrogance of 19th-century elitism). But its core insight — that crowds make people lose rationality — precisely hits an eternal phenomenon.
And for investors, there is one never-ending, largest crowd of all — the market.
Two: Crowd Characteristics That Perfectly Match Market Sentiment
The crowd traits Le Bon describes can be used almost verbatim to describe the market.
First, emotional contagion. Emotions spread like a virus in a crowd, and they get amplified. One person's fear infects a group, which turns into collective panic. The stampede during a market crash is pure emotional contagion — no one is calmly analyzing fundamentals at that moment; everyone is driven by fear to sell. Similarly, the euphoria at the top of a bubble is contagion of greed.
Second, a drop in collective intelligence. Le Bon says the intelligence of a crowd is lower than that of any individual in it — the crowd tends toward the lowest common denominator, not the highest wisdom. In markets, this shows up as — collective judgment is often astonishingly stupid. The meme stocks and crypto mania of 2021 involved many smart people, but once a crowd formed, collective behavior became deeply irrational.
Third, susceptibility to simple slogans. Le Bon argues that crowds don't accept complex arguments; they only accept simple, repeated, emotional assertions. In markets, what moves a crowd most is never rigorous analysis, but a simple powerful narrative — "this time is different," "AI changes everything," "fear of missing out." This echoes Shiller's "narratives" and Cialdini's "social proof."
Three: The Key Lesson for Investors — You Are Also in the Crowd
The deepest lesson this book offers investors is not "look how others get swept up by the crowd," but — acknowledge that you yourself are also in that crowd, and you will also be infected.
Most people reading 'The Crowd' will feel a superiority — "those swept-up sheep are so stupid, but I am clear-headed." But that very superiority is the most dangerous thing — because the terrifying thing about crowd emotion is exactly that it takes hold of you without your awareness, while you think you are being rational.
When the market is euphoric and you buy, you feel it's a "rational decision based on fundamentals." When the market is panicked and you sell, you feel it's "prudent risk management." But often, you are simply infected by crowd emotion, and you use rationality to rationalize your emotional behavior (remember Kahneman — System 1 makes the decision, System 2 makes up the story).
Le Bon would tell you — you are not as independent as you think.
The way to counter this is not "believe you are clear-headed" (that's exactly the trap), but — build mechanisms that isolate your decisions from crowd emotion: enforce a cooling-off period when emotions are high, use pre-written rules instead of on-the-spot judgment, deliberately distance yourself from market noise, and before a major decision ask yourself "Am I making an independent judgment, or am I being infected by the crowd?"
The true contrarian investor is not the person who is "unaffected by the crowd" (no one is fully immune), but the person who knows they will be affected and has built defenses.
Four: My Fundamental Criticisms of This Book
First, it's full of 19th-century elitist bias.
Le Bon's contempt for the "crowd" carries strong class and era prejudices. He describes the crowd as inherently stupid, needing to be guided by elites. This elitism is not only morally questionable, but also factually one-sided — crowds are not always stupid. "Wisdom of crowds" is real in many situations: market prices are largely efficient most of the time (efficient market hypothesis), prediction markets, crowdsourcing, and collective decisions often beat individual experts. Le Bon sees only the "stupid" side of crowds and completely ignores the "wise" side.
Second, it absolutizes crowd irrationality.
Le Bon argues that crowds are necessarily irrational. But reality is more complex — crowds are irrational under certain conditions (high emotion, low information, presence of agitators), but rational under other conditions (sufficient information, independent judgment, diversity). Markets are relatively efficient most of the time (crowd rationality) and only break down at extreme moments (crowd madness). Le Bon mistakes "extreme crowd madness" for "the normal state of crowds" — this is overgeneralization. What investors need is precisely the judgment — is this the normal state of "crowd rationality," or the extreme moment of "crowd madness"? Le Bon's absolutist framework doesn't provide that judgment.
Third, it lacks scientific rigor.
Written in 1895, 'The Crowd' is more like Le Bon's "observations and assertions" than rigorous scientific research. It is full of unproven generalizations and vivid but one-sided examples. Modern social psychology research on group behavior (conformity experiments, group polarization, social identity) is far more precise and rigorous than Le Bon. Le Bon raised important questions, but his "answers" are often intuition and prejudice, not science. Read it with this awareness — it's pioneering, but not reliable.
Fourth, it carries the danger of being "reverse-engineered."
Ironically — this book that reveals "how crowds are manipulated" was later used by many manipulators (including some totalitarian propagandists) as a manipulation manual. Le Bon describes how crowds are controlled by simple slogans, repetition, and emotional arousal — these descriptions can be used either to "defend against manipulation" or to "execute manipulation." This is the same fate as Cialdini's 'Influence' — a book meant to protect people became a tool to harm them.
Five: Le Bon vs. Shiller — Two Takes on Crowd Emotion
Le Bon and Shiller ('Irrational Exuberance') both talk about "how crowd emotion drives markets," but their style and rigor are vastly different.
Le Bon is 19th-century intuitive assertion — with keen observation, he crystallized the insight that "crowds are irrational," but his arguments are full of bias and generalization, lacking scientific basis.
Shiller is modern empirical research — using CAPE data and systematic analysis of historical bubbles, he put "how narratives drive market sentiment" on relatively solid empirical ground.
Le Bon raised the problem (crowds can be irrational); Shiller gave relatively rigorous analysis (how narratives create irrationality and how to identify it).
Combined — use Le Bon to get an alert about "crowd emotion" (including the alert that you are also in the crowd); use Shiller to get concrete tools to identify "narrative peaks." Le Bon gives you an intuitive warning; Shiller gives you actionable analysis.
But most importantly, both point to the same investment truth — the market is not a rational pricing machine; it is a massive crowd full of emotion and prone to periodic madness. Understanding the psychology of this crowd is closer to the essence of the market than understanding any financial model.
Six: Final Thoughts
I read this book with conflicting feelings — it is full of biases and arrogance I disagree with, yet its core insight hits the essence of markets with uncanny precision.
The biggest takeaway for me is not "seeing the stupid people swept up by the crowd," but a much humbler realization — I myself am in that crowd, I will also be infected, and when I am infected, I won't even notice.
This is the hardest and most important lesson. Because most investors (including me) have an illusion — "other people get swept up by market emotion, but I am clear-headed, independent, and rational."
Le Bon would coldly tell you — No, you are not as independent as you think. When everyone is greedy, your 'rational buy' is likely an infection; when everyone is fearful, your 'prudent stop-loss' is likely a contagion.
Acknowledging this is the first step to countering crowd emotion. Because only when you admit "I can be affected" will you build mechanisms to isolate yourself from the crowd — cooling-off periods, rules, distance from noise. And those who are confident "I can't be affected" are exactly the ones most likely to be swept away, without even noticing, in crowd euphoria and panic.
The crowd Le Bon described in 1895 has put on new clothes today — it's called social media trending topics, financial influencer call-outs, retail investor forum frenzies, and crypto community FOMO. Technology has changed, the medium has changed, but the essence of crowd psychology remains unchanged for over a century.
Understanding this never-ending crowd, and understanding that you yourself are also in it —
This may be the deepest and hardest lesson in investing, deeper than any analytical technique.
