Simple math is a great way to understand a system’s behavior. I picked up this trick from Warren Buffett’s writing and speaking. Warren often figures out which mathematical elements drive behavior of a stock or industry, and then uses that to set a boundary on his investment decisions. He gave a great analysis in February 2000 of why the first internet bubble had to pop. Three weeks later, it did.

His analysis depended entirely on noting that valuations in the internet companies were assuming profit growth of 15%, while the economy as a whole was growing at 2.5%, and profits were remaining a constant share of the economy. As he put it, “mathematically, that relationship can not continue to hold. I don’t know what will collapse, I don’t know who the survivors will be—and there will be many of them—but I do know that eventually the house of cards will tumble. It has to.”

The Simple Math of Wealth Inequality

Thomas Pitteky’s new book about income inequality is apparently making a big splash. I haven’t read it, yet, but I’ve been told he is very sympathetic to my point of view. Here’s my analysis, before reading the book.

I’ve long held that the driver of wealth inequality is much simpler than policy, philosophy, or ideology. It’s simple mathematical fact, given our tax rates.

I finally ran some numbers.

Starting position: rich own 25%, everyone else, 75%
Overall tax rate on everyone else, 39% (25% federal + 14% FICA)
Overall tax rate on the Rich, 17% (mainly capital gains)
Assuming the Rich can get an average ROI of 15%, while everyone else 10%
(a reasonable assumption, given that the entire class of high risk/high return investments requires one to be an accredited investor. I.e., rich.)

With these assumptions, in 50 years (say, 1960 to 2010), the income distribution goes from rich 25%, everyone else 75% to rich 85%, everyone else 14%.

If we assume that both groups get equal returns on their money, rather than the rich getting higher returns, we still go from 25/75 to 48/51 in just 50 years

The Rich Get Richer, Purely By Virtue of Ownership

As long as the overall tax rate on the rich is lower than the overall tax rate on the poor, even independent of the range of investment opportunities available (and the rich also have enough money to have a portfolio of large-enough bets that a single winner will ultra-increase their net worth), the rich will eventually own everything.

This is independent of whether they work harder, whether they are more committed, whether they “create jobs,” or anything else. It’s purely based on their after-tax rates of return. (And as for them being job creators, note that to the extent that they can lay people off, their rates of return will increase. Hiring decreases it.)

I don’t understand why this simple mathematical fact never comes up in these discussions.

Even If The Rich Allocate Capital Poorly, They Still Win

If you run the numbers, it doesn’t matter if the rich get below-market returns. Berkshire Hathaway, Warren Buffett’s company, has only gotten market-level returns in recent years. But he’s still owning more of the economy than you are, every year.

The tax rate differential is high enough that Warren Buffett’s interest income still has a better after-tax return than you have on your entire income.

Income inequality is simple math

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