In a rising market, the investors taking the most risk generate the highest returns, making them appear brilliant. However, this same aggression ensures they will be hurt the most when the market turns. This dynamic creates a powerful incentive to increase risk-taking, often just before a downturn.

Post-mortems of bad investments reveal the cause is never a calculation error but always a psychological bias or emotional trap. Sequoia catalogs ~40 of these, including failing to separate the emotional 'thrill of the chase' from the clinical, objective assessment required for sound decision-making.

Investment risk should be assessed using a 2x2 matrix plotting financial capacity against psychological risk tolerance. A high ability but low willingness is 'defensive,' while a low ability but high willingness is 'naive' and foolish, as it courts consequences the plan cannot survive.

The primary driver of market fluctuations is the dramatic shift in attitudes toward risk. In good times, investors become risk-tolerant and chase gains ('Risk is my friend'). In bad times, risk aversion dominates ('Get me out at any price'). This emotional pendulum causes security prices to fluctuate far more than their underlying intrinsic values.

Conventional definitions of risk, like volatility, are flawed. True risk is an event you did not anticipate that forces you to abandon your strategy at a bad time. Foreseeable events, like a 50% market crash, are not risks but rather expected parts of the market cycle that a robust strategy should be built to withstand.

Investors should establish a baseline risk level on a 0-100 scale based on personal factors like age and wealth. This becomes their default posture. The more advanced skill is then to tactically deviate from this baseline—becoming more or less aggressive—based on whether the prevailing market environment is offering generous or precarious opportunities.

People justify high-risk strategies by retroactively fitting themselves into a successful subgroup (e.g., 'Yes, most investors fail, but *smart* ones succeed, and I am smart'). This is 'hindsight gerrymandering'—using a trait like 'smartness,' which can only be proven after the fact, to create a biased sample and rationalize the risk.

The convergence of geopolitical, economic, and technological stressors overwhelms human working memory, causing a 'cognitive load collapse.' This isn't just market uncertainty; it’s a specific, well-documented psychological failure mode where decision-making abruptly degrades.

Based on Daniel Kahneman's Prospect Theory, once investors feel they are losing money, their behavior inverts. Instead of cutting losses, they adopt a "double or nothing" mentality, chasing high-risk gambles to escape the psychological pain of loss.