The Ego Traps That Wreck Portfolios

What You Will Learn From This Article

• What denial and self-deception bias is, and why it makes bad positions get worse for longer than they should
• What overconfidence is, and why Munger considered humility one of the genuine secrets behind his and Buffett’s success
• Why these look like opposite problems but share the same underlying cause
• How to build in checks that catch both before they get expensive

Denial and overconfidence seem, on the surface, like opposite failures. One makes people shrink from bad news and cling to a losing position. The other makes people charge forward with far more certainty than the facts actually support. Charlie Munger traced both back to the same root cause: an ego that has become too invested in being right to actually notice when it isn’t.

Denial and Self-Deception

Denial bias, one of the tendencies from Munger’s 1995 Harvard speech “The Psychology of Human Misjudgment,” describes how people instinctively distort or reject information that threatens a belief they’re heavily invested in, financially or psychologically. The word “invested” is doing real work here. The more money, time, or public commitment someone has already put behind a decision, the harder their mind works to protect that decision from being seen as a mistake, often well before they consciously realise they’re doing it.

In investing, this shows up as a very specific pattern. An investor buys a position, new information emerges that should reasonably change their view of it, and instead of updating their view, they find a reason to dismiss the new information: the source is unreliable, the market is overreacting, the fundamentals haven’t really changed. Sometimes those objections are genuinely valid. Often, on close inspection, they’re the mind protecting itself from an uncomfortable admission rather than a fair reading of the evidence.

The cost is straightforward: a losing position that a clear-eyed assessment would have exited gets held for longer, sometimes much longer, because admitting the original decision was wrong feels worse than the ongoing financial cost of being wrong.

Overconfidence and the Missing Ingredient: Humility

The opposite-looking problem is overconfidence, and Munger spoke about its remedy more than the flaw itself. Across multiple interviews and Berkshire Hathaway shareholder meetings, he credited a significant part of his and Buffett’s success to a consistent effort not to be arrogant, and to know precisely where their own knowledge actually ended.

Overconfidence in investing rarely announces itself as arrogance. It usually shows up as an investor holding an oversized, poorly diversified position because they feel certain about an outcome that is, in reality, no more knowable to them than to anyone else. It shows up as skipping the research step because a previous success created a feeling of expertise that hasn’t actually been earned in the new situation. It shows up as dismissing a well-reasoned counterargument too quickly, because entertaining it seriously would mean acknowledging genuine uncertainty.

The financial cost tends to be concentrated and sudden rather than slow, unlike denial’s gradual drag. An overconfident, oversized bet that goes wrong can do far more damage in a single event than years of a merely underperforming position sitting in denial.

The Shared Root: An Ego That Needs Protecting

Denial protects the ego from a past decision by refusing to see it clearly. Overconfidence protects the ego in the present by inflating a sense of current knowledge or skill beyond what’s actually justified. Both are, at bottom, the same defensive manoeuvre aimed in different directions, backward for denial, forward for overconfidence, and both exist to avoid the same uncomfortable feeling: genuinely not being as right, or as capable, as one would like to believe.

This is why Munger discussed them as related ideas rather than isolated quirks. Addressing one without the other misses the underlying pattern. An investor who has trained themselves to admit past mistakes quickly, but who is still prone to inflated confidence about new decisions, has only solved half the problem.

Building in Checks for Both

• Before making a significant investment decision, write down specifically what would have to be true for it to go wrong, not just why you believe it will go right
• When new information arrives that challenges an existing position, notice your first instinct to dismiss it, and deliberately ask whether that dismissal would hold up if a trusted, skeptical friend heard your reasoning out loud
• Keep a simple record of your own past predictions and their outcomes; most people’s actual track record, seen honestly in writing, is humbling in a useful way
• Treat position size as a direct expression of how much genuine uncertainty remains, rather than how confident you currently feel

Key Takeaways

• Denial and self-deception bias causes investors to distort or reject information that threatens a decision they’re already committed to, keeping bad positions alive longer than they should be
• Overconfidence causes investors to act with more certainty than the facts justify, often producing large, sudden losses from oversized bets
• Munger traced both back to the same root: an ego defending itself, either backward-looking or forward-looking
• Writing down what would have to be true for a decision to fail, and tracking your own prediction record honestly, are practical defences against both

Frequently Asked Questions

How can I tell if I’m in denial about a losing position, rather than making a reasoned decision to hold it?

Ask whether you would buy the position today, at its current price, with fresh eyes and no history with it. If the honest answer is no, but you’re still holding on because selling would mean admitting the original decision was wrong, that’s a strong signal of denial rather than reasoned conviction.

Isn’t some confidence necessary to invest at all?

Yes, and Munger wasn’t arguing for constant self-doubt. The distinction is between confidence that’s proportionate to genuine knowledge and analysis, and confidence that’s simply inflated by past success, a good story, or the discomfort of admitting uncertainty.

Why does Munger connect humility specifically to investment success?

Because humility keeps an investor’s circle of competence honest. Someone who admits what they don’t know is far more likely to stay out of situations beyond their genuine understanding than someone whose self-image requires appearing knowledgeable about everything.

Does keeping a record of past predictions actually help, or is it just busywork?

It genuinely helps, because human memory tends to selectively recall being right more often than being wrong. A written record removes that selective editing and gives a more honest picture of your actual track record, which is a direct check against overconfidence.

Can these ego traps affect professional fund managers too?

Yes. Munger’s observations applied broadly across business and investing, not just individual retail investors. Professional investors are equally capable of denial about a losing position or overconfidence about a new one; institutional processes exist partly to catch exactly these failures.

This article was researched and drafted with the assistance of AI tools and reviewed for accuracy. It is general information, not personalised financial advice. Historical and biographical details were verified against publicly available sources at the time of writing, but please confirm any date or fact that matters to you independently before relying on it.