For decades, investing followed a simple formula: some cash for safety, bonds for income, and stocks for growth. This approach was supported by decades of low inflation, steady bond yields, and predictable compounding.
But the environment has changed. Inflation has run higher, the money supply has expanded rapidly, and government debt has reached record levels. These shifts challenge some of the most common financial assumptions: the hurdle rate for returns, the role of the 60/40 portfolio, and the sustainability of the 4% withdrawal rule.
This article examines why the math looks different today and why even long-standing rules need to be re-examined.
The Real Hurdle Rate
For years, investors were told that 6 to 8 percent annual returns were strong. Historically, they were. But those returns are measured in dollars, and dollars lose value over time.
Since 2000, the U.S. money supply (M2) has grown by about 6 to 7 percent per year, rising from roughly $4.7 trillion to more than $22 trillion by 2025.²³ During the COVID-19 pandemic, it surged nearly 40 percent in just two years.⁶
At the same time, inflation has run well above target. In 2022, inflation reached 9.1 percent year-over-year, the highest in four decades.¹ Even in 2023 and 2024, prices for essentials like housing, food, insurance, and healthcare rose much faster than headline averages, often in the 7 to 12 percent range.¹
This is why many analysts argue that official CPI does not fully capture lived inflation. Real erosion comes from the combination of money supply growth (debasement) and consumer price inflation. While there is overlap between the two, together they illustrate why purchasing power has been declining more sharply than reported.
Estimated Annual Erosion of the Dollar
| Factor | Annual Rate |
| Money Supply Growth (Debasement) | ~6–8%²³ |
| CPI Inflation (Official) | ~3–4%¹ |
| Real-Life Inflation (Housing, Healthcare, Essentials) | ~8–12%+¹ |
| Estimated Total Erosion | 7–12%+ annually |
This creates a “hurdle rate,” which is the minimum return needed just to stand still.
If your portfolio grows at 6 percent while erosion runs higher, you are not building wealth. You are quietly losing value in real terms, even if account balances appear larger. Inflation and debasement do not just add up year after year. They build on each other, magnifying the effect the longer it goes on.
The 60/40 Trap
For decades, the standard retirement portfolio was 60 percent stocks and 40 percent bonds. It was balanced, conservative, and perceived as dependable—at least in the past.
But that math no longer works. Bonds have limited upside, and after inflation, they often produce negative real returns. Instead of acting as a stabilizer against stock declines, they have increasingly moved in the same direction as equities.
Historically, most 60/40 portfolios returned 4 to 7 percent per year.⁵ But when erosion runs at higher levels, that return falls short from the very beginning. Retirees who appear comfortable on paper may find their purchasing power eroding much faster than expected. Because retirement can last 20 to 30 years or more, the gap compounds relentlessly.
We used to think of 7 percent returns as powerful because money could double every 10 years. The same math works in reverse. If inflation and debasement run higher than portfolio growth, purchasing power can be cut in half just as quickly.
The Collapse of the 4% Rule
The “4 percent rule” became popular in the 1990s. Under this framework, a retiree with $1 million could withdraw $40,000 per year and expect their savings to last 30 years.
But that assumption rested on inflation near 2 percent and portfolio growth near 7 percent. Today, the reality looks different.
Core household expenses such as housing, insurance, and healthcare have risen much faster than official CPI averages in recent years.¹ At the same time, many portfolios have only returned 4 to 7 percent annually.⁵
That means a $40,000 withdrawal is not just interest. It reduces principal, because the portfolio itself is losing value in real terms. Research groups still estimate sustainable withdrawal rates around 3.7 to 4.7 percent.⁴⁵ However, those models assume lower inflation. If erosion compounds at higher levels, the rule breaks down.
What was once a retirement plan becomes, in practice, a gradual liquidation of assets. For example, a $1 million portfolio earning 5 percent annually but facing 8 percent inflation loses roughly 3 percent in real purchasing power each year. After just a decade of $40,000 withdrawals, the real value of the portfolio may lose a significant portion of its purchasing power, making 20 or 30 years of stability much harder to achieve without meaningful lifestyle adjustments.
The Forced Risk Curve
These shifts create a new reality for investors.
Cash may look safe, but it almost guarantees loss of purchasing power during higher inflation.
Bonds may feel steady, but after inflation, their returns have sometimes been negative in real terms.
Stocks are one of the few traditional asset classes with potential to outpace inflation, because they tend to benefit from money supply growth and the repricing of assets in inflated dollars.
Scarce assets like gold have historically preserved purchasing power because they cannot be created at will.
This does not mean chasing risk for its own sake. It means recognizing that the old definition of “conservative”—staying in cash and bonds—may not always preserve purchasing power. In today’s environment, conservative could mean something different: durability over decades, even if it requires tolerating more volatility.
Final Takeaway
The financial environment has changed. The money supply has expanded, inflation has run above target, and debt levels have climbed. These forces challenge long-standing financial rules that were built for a different era.
The 60/40 portfolio, the 4 percent rule, and the idea that 6 to 8 percent nominal returns are sufficient all assume inflation remains low and stable. If erosion compounds at higher levels, the math no longer works.
The takeaway is not prescriptive, but simple. Understanding the difference between compounding on paper and compounding in reality has never been more important. And the real kicker is this: many of the financial planning rules that retirement and wealth plans have relied on for decades may be structurally challenged before they even begin.
Disclaimer
This content is for educational purposes only and does not constitute investment advice or a recommendation to buy or sell any financial instrument. Readers should conduct their own research or consult a qualified advisor before making financial decisions.
Chris Millar
Financial Advisor, Millar Financial
Affiliated with Wilde Wealth Management Group
7025 N Scottsdale Road, Suite 115 & 110
Scottsdale, AZ 85253
Securities and advisory services offered through Cetera Advisors LLC, member FINRA/SIPC, a broker/dealer and Registered Investment Adviser. Cetera is under separate ownership from any other named entity.
Works Cited
¹ Bureau of Labor Statistics. Consumer Price Index. U.S. Bureau of Labor Statistics, 2025.
² Investopedia. M2 Money Supply. IAC Publishing, 2025.
³ Lacey, Laurence. The Relationship Between the U.S. Broad Money Supply and Asset Markets. arXiv, 2021.
⁴ Money.com. The Popular 4% Rule for Retirees Just Got an Update. Aug. 15, 2025.
⁵ Morningstar. Reevaluating the 4% Withdrawal Rule. Morningstar Retirement Research, Feb. 27, 2025.
⁶ Yahoo Finance. U.S. M2 Money Supply Hits Record Highs. 2025.