A plan you understand and keep beats a smart plan you abandon.
Simple beats clever.
Four ways to invest for ten years. Tap the best.
Hundreds of experts, two layers of fees. The plain fund came out ahead.
← Red LinesRed Line 23 of 48 The idea The numbers Where you see it Where it bends This game’s numbersHow strong the proof isBGood proof, with limits Where it comes from
The best plan on paper is worth nothing if you drop it in the first bad year. A plain plan you understand is one you can keep.
A simple plan at 6% a year, kept for 20 years: €10,000 becomes about €32,000. A clever one at 8%, dropped after a 30% fall in year 6 and left in cash: about €12,000.
A handful of broad index funds in fixed shares, topped up every month, is a whole plan. It is dull on purpose.
Simple is not careless. Still know what you own.
Berkshire Hathaway: 2017 letter to shareholders (the bet’s final scorecard)Conversable Economist: Buffett’s bet, 10 years later
Simple equal splits held up against clever optimised plans in real data, but the evidence is about portfolios, not about whether people keep their plans.
- Optimal Versus Naive Diversification: How Inefficient is the 1/N Portfolio Strategy? Victor DeMiguel, Lorenzo Garlappi & Raman Uppal, Review of Financial Studies 22(5), 1915-1953, 2009
Checked 2 Nov 2026 · How we grade
- A Strong proof: Many good studies or long official data, from different teams or countries, point the same way.
- B Good proof, with limits: Solid studies agree on the direction, but the size varies, or the data covers few places or few kinds of people.
- C Mixed proof: Some good studies for, some against, or the evidence covers only part of the line.
- D Thin proof: Mostly one book’s argument, one survey or stories. It may be wise, but it has not been tested well.
- = True by the sums: It follows from arithmetic, so no study can overturn it. We still show what real data says.
William J. Bernstein, The Four Pillars of Investing (2002). In our words, not quoted.
See it in numbers: Index funds · Your plan (From Zero)
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