Mental Model · Economics
Opportunity Cost
Personal recommendation by Marshall Delpé. Not made by Marshalldelpe.com.
Opportunity Cost
Mental Model · Economics·

Every yes quietly sends a no to something else. Read the receipt.
What it does: Reminds you that the true cost of any choice is the best alternative you gave up to make it. Every dollar, hour and unit of attention spent on one thing is not available for the next best thing.
Who it's for: Anyone making decisions about money, time or career — which is everyone. Especially useful when a choice looks "free" or when you are comparing a sure thing against a better but less obvious option.
Why I use it: It is the filter I run every major decision through. A purchase is not just its price — it is what that money would have become if it had been invested and compounded. An extra shift is not just extra pay — it is time not spent building assets, training or resting. Munger said intelligent people make decisions based on opportunity costs, and once you see them they are everywhere.
Tradeoffs: Taken to an extreme it causes analysis paralysis and makes it hard to enjoy anything. You cannot perfectly measure the road not taken, so treat it as a compass, not a calculator.
Alternatives: Inversion (ask what would make a choice fail), second-order thinking (and then what?), and Bezos's regret-minimisation framework.
This is a personal recommendation, not a paid promotion.
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The 48 Laws of Power
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Read it so you can spot the person at work who already did.
What it does: Robert Greene distils 3,000 years of history — Machiavelli, Sun Tzu, Bismarck, Louis XIV, con artists and courtesans — into 48 laws describing how power is gained, held and lost. Each law comes with historical stories of people who followed it and people who broke it, plus the reversal: when the law doesn't apply.
Who it's for: Anyone who works with people — in a hospital, a company, a negotiation or an investment deal — and wants to understand the unspoken dynamics at play. Especially useful if you've ever been blindsided by office politics or someone else's agenda.
Why I use it: I read it as a field guide to human behaviour rather than a playbook. It helps me recognise manipulation when I see it, protect my reputation, and stay calm instead of reacting. Laws like "Never outshine the master", "Guard your reputation with your life" and "Say less than necessary" have saved me from mistakes at work. It pairs well with Munger's psychology of human misjudgment, which you'll find in Poor Charlie's Almanack.
Tradeoffs: Some of the laws are ruthless, and following them literally can cost you trust and relationships. It's long and repetitive in places, and it's best read defensively — to understand power — not as permission to be cold or deceptive. The stories are selective history, not rigorous research.
Alternatives: The Laws of Human Nature and Mastery by Robert Greene, How to Win Friends and Influence People by Dale Carnegie (the warmer approach), Influence by Robert Cialdini (the research-backed version).
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The Art of War
Book · Sun Tzu·

Ancient battle advice that works surprisingly well on salary negotiations.
What it does: An ancient Chinese treatise on military strategy, traditionally credited to the general Sun Tzu, written around the 5th century BC. In 13 short chapters it covers planning, positioning, deception, intelligence and when to fight — and when not to. Its core idea: the best victory is the one won without fighting.
Who it's for: Anyone dealing with competition or conflict — in business, negotiation, investing, sports or office politics — who wants timeless principles about preparation, patience and knowing the terrain.
Why I use it: It is short enough to reread every year, and every reread lands differently. "Know the enemy and know yourself" maps directly onto investing and staying within your circle of competence, and the emphasis on avoiding unnecessary battles is a reminder that the strongest position is often the one where you never have to fight. It pairs naturally with The 48 Laws of Power.
Tradeoffs: The aphorisms are compressed and sometimes cryptic, so translation quality matters a lot. It is easy to over-apply military metaphors to everyday life, and the original is about war, not business — the connections take reflection to make.
Alternatives: The 48 Laws of Power and The 33 Strategies of War by Robert Greene, The Book of Five Rings by Miyamoto Musashi, and On War by Carl von Clausewitz.
As an Amazon Associate I earn from qualifying purchases, at no extra cost to you. I only recommend what I actually use.