FIRE BTC

FIRE BTC

🚨 Emergency Economics

FIRE BTC #51 - Your emergency fund is making you poorer

Trey Sellers's avatar
Trey Sellers
Oct 16, 2025
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You’ve probably heard it a hundred times:

“The best investment you’ll ever make is a 6–12 month emergency fund.”

It sounds prudent. Responsible. Mature.

And in a world that sells fear, it feels right.

But that’s the problem.

The entire concept of an “emergency fund” is built on fear—fear of job loss, fear of income disruption, fear of uncertainty. It’s advice that optimizes for the low-probability disaster instead of the high-probability reality that your money will quietly melt away in the meantime.

This kind of guidance has been repeated so often in the personal finance world that it’s rarely questioned. It’s comforting to know you have a pile of cash sitting there “just in case.” And for people with zero savings or chronic spending issues, maybe that message has some merit.

But for anyone who’s thinking seriously about financial independence—or about the long-term engineering of their wealth—it’s terrible advice.

The hidden cost of “safety” is compounding that never happens.

That’s what this week’s issue is about. We’re going to put numbers behind the opportunity cost of holding cash, and then we’ll go a step further—using probability-based reasoning to test whether the traditional logic even holds up when you factor in the risk it’s supposedly protecting you from.

By the end, you’ll see why your liquid assets—stocks and bitcoin—are not only capable of serving as your emergency fund, but are mathematically superior to the conventional approach.


👻 If you’re new here, FIRE BTC explores the intersection of bitcoin and financial independence — where fear ends and rationality begins.


💡 Quantifying the Hidden Cost of “Safety”

Let’s make this concrete.

Say your monthly expenses are $5,000.

Conventional wisdom says you should stash away 6 months of expenses in cash — about $30,000 — in case something bad happens.

Now, let’s stretch that advice over a 10-year horizon and see what happens.

We’ll be generous and assume you’re not keeping it in a checking account earning nothing. You’re earning 4% in a high-yield savings account (HYSA).

We’ll compare that against a popular investment choice of the FIRE community and the apex predator of savings vehicles — the S&P 500 and bitcoin — using their respective 10-year (12%) and 5-year (~59%) CAGRs.

At 4%, that “safe” pile of cash can’t keep up with inflation. The money supply (M2) grows roughly 7%/yr, which means the dollar’s purchasing power roughly halves over a decade. So a 4% yield still leaves you ~3% poorer per year in real terms.

Meanwhile, the same $30,000 invested in stocks grows to just over 3× your money, and in bitcoin, it grows to ~64×!

So you’re trading massive future wealth for “peace of mind” today, which is really nothing more than lost freedom.

And it’s the part almost nobody quantifies when they preach the importance of cash reserves. They focus on the emotional benefit of feeling “secure,” but never on the mathematical consequence of sitting on dead money for a decade.

Ok…at this point, you’re probably thinking, “But what if I lose my job?!?!” Let’s test this with the same probabilistic reasoning we explored in FIRE BTC #29, “Expected Value Thinking”. If you haven’t read that issue, now’s a great time:

🧠 Expected Value Thinking

Trey Sellers
¡
May 10, 2025
🧠 Expected Value Thinking

One of the biggest traps on the road to financial independence is craving certainty in an uncertain world. We want clear answers, safe plans, guaranteed wins. But life and money don’t work like that.

Read full story

Spoiler: even when you handicap for risk, the math still comes out massively in favor of investing your liquidity.


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⚖️ Accounting for Risk the Rational Way

Now that you’re caught up, let’s make this scenario a little more realistic.

The whole point of an “emergency fund” is to protect against the loss of income. So let’s assume that happens — you lose your job, your paycheck stops, and you have to live off savings for six months before finding a new one.

Instead of imagining you dump your entire portfolio at once (which almost no one would do), we’ll assume you sell a portion each month to cover expenses while your investments remain mostly intact and continue to fluctuate with the market.

Here’s how we’ll model it:

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