Gardner notes that whenever he has broken his own rule and invested an "exciting amount" into a new idea, it has generally failed. This emotional excitement leads to poor decision-making and oversized bets on unproven theses. Strict discipline on initial position sizing is a crucial defense against one's own biases.
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Jeff Aronson warns that prolonged success breeds dangerous overconfidence. When an investor is on a hot streak and feels they can do no wrong, their perception of risk becomes warped. This psychological shift, where they think "I must be good," is precisely when underlying risk is escalating, not diminishing.
The worst feeling for an investor is not missing a successful deal they didn't understand, but investing against their own judgment in a company that ultimately fails. This emotional cost of violating one's own conviction outweighs the FOMO of passing on a hot deal.
Daniel Mahr's first investing experience was successfully flipping dot-com IPOs. However, turning those wins into giant losses by straying from his original thesis taught him a formative lesson about the dangers of overconfidence and the necessity of a disciplined, systematic approach.
True understanding of a business often comes only after owning it. Taking a small (e.g., 1%) starter position can initiate the research process and shift your perspective from a casual observer to a critical owner, revealing nuances and risks not apparent from the outside.
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.
To pursue massive upside, one must first survive. Gardner mitigates risk by never allocating more than 5% of his portfolio to any new position. This discipline prevents catastrophic losses from a single bad idea, ensuring he stays in the game long enough for the big winners to emerge.
Our brains are wired to find evidence that supports our existing beliefs. To counteract this dangerous bias in investing, actively search for dissenting opinions and information that challenge your thesis. A crucial question to ask is, 'What would need to happen for me to be wrong about this investment?'
Contrary to the "buy the dip" mentality, David Gardner's strategy involves adding to positions that have already appreciated. This "add up, don't double down" approach concentrates capital in proven performers and prevents throwing good money after bad, which he identifies as the primary way investors go broke.
Gardner argues that avoiding losses stifles innovation and learning. True long-term gains, like in venture capital, come from embracing risk and accepting that many small losses are necessary to find the few massive winners that drive all returns.
McCullough advocates for a "promiscuous" investment strategy, quickly moving capital to where signals are strongest. He argues that emotional attachment to winning positions, or "bag holding," is the primary way investors lose ground. The goal is to compound returns by avoiding drawdowns, not by marrying a single investment thesis.
