The Opportunity Cost Lens
Evaluate every purchase by what the money could earn if invested instead
The Opportunity Cost Lens is a mental framework for evaluating spending decisions by considering not just the purchase price but also the future earnings that money would have generated if invested instead. Collins argues that most people think about money only in terms of what it can buy right now, and this single-level thinking keeps them poor. Wealthy thinking requires understanding that when you spend money, you lose not just the amount spent but also everything that money would have earned, and everything those earnings would have earned, compounding indefinitely.
Collins illustrates with the example of a $20,000 car. At an 8% return, that $20,000 earns $1,600 in the first year alone. Over 10 years of car ownership, the opportunity cost is at least $16,000 in lost earnings, not counting the compounding of those lost earnings. The true cost of the car approaches $36,000 or more. And since the $20,000 is gone forever, the lost earning potential continues indefinitely.
Collins identifies four levels of monetary thinking: spending (poor), investing for returns (middle class), investing while reinvesting and only spending 4% (upper middle class), and fully reinvesting all returns to let compounding work its magic (wealthy). He uses the example of Mike Tyson, who earned $300 million but went bankrupt because he understood money only at level one. The framework is not about never spending money but about fully understanding the true cost of every spending decision.
- When you spend money, you lose not just the amount but everything it would have earned forever
- Opportunity cost is the evil twin of compound interest
- Think about what your money can earn, not what it can buy
- Financial independence means your compounding exceeds your opportunity cost of spending
- Borrowing money to buy something means choosing to pay much more than the sticker price
- Every spending decision is simultaneously an investment decision
- Even a $100 bill has four fundamentally different values depending on how you think about it
- Before any major purchase, calculate the 10-year opportunity costTake the purchase price and multiply by 8% per year for 10 years. A $20,000 purchase costs roughly $36,000 in real terms when you account for the lost earnings. For ongoing expenses (subscriptions, memberships), multiply the annual cost by 25 to see the investment portfolio equivalent.
- Ask yourself what level of monetary thinking you are applyingLevel 1: What can this money buy? Level 2: What could this money earn? Level 3: What could the earnings earn? Level 4: How does this affect my compounding over decades? Train yourself to think at levels 3 and 4.
- Evaluate purchases against your financial independence timelineFrame every discretionary purchase as a choice between the item and a faster path to financial independence. A $500 monthly car payment, if invested instead at 8%, becomes roughly $450,000 over 20 years. Ask: is the car worth $450,000 of future wealth?
Mike Tyson earned approximately $300 million during his boxing career with a lifestyle reported to cost $400,000 per month. He understood money only at level one: what it can buy right now. He went bankrupt. Collins suggests that if Tyson had understood money at even level two, investing his earnings at a modest return, he would have been one of the wealthiest athletes in history.
Collins developed this framework through decades of observing how different people think about money. He was struck by the case of Mike Tyson, who earned $300 million as one of the most dominant boxers in history but went bankrupt due to a reported $400,000 per month lifestyle. Despite his enormous earnings, Tyson understood money only in terms of buying things. Collins contrasts this with Warren Buffett's approach of thinking about investments as ownership of businesses, leading to two radically different outcomes with vastly different starting points.