At the beginning of this year, billionaire Warren Buffett won a bet that made him $1 million richer. For the rest of us, the outcome of this wager teaches us how unique the investing profession is in the great scheme of things.

Buffett, as you probably know, is a billionaire who buys companies at a discounted price and hopes to hold them forever. He doesn’t hedge his positions, read charts or change his portfolio very much from decade to decade. He wagered $1 million that investing in the simple S&P 500 index over the ten years ending last December would beat a portfolio of five hedge funds, each with tons of Wall Street experience and trading acumen. The final tally wasn’t even close: The index returned 125.8% over the time period, while the hedge funds, collectively, were up 36%.

Most of us never stop to realize how unique it is to invest in the stock market, very different from pretty much everything else we do in our daily lives. Those hedge funds were paid massive amounts of money to accumulate the data and expertise needed to have an edge over every other investor. The problem is that there is no guarantee that research and expertise actually confer an advantage, particularly if there is active trading involved. If you have trouble believing that expertise doesn’t translate into high returns, try to name a superstar trader or market timer. Chances are you can name a few remarkable individuals in just about every other field—sports, sciences, the arts; all the normal careers where skill and hard work are important. But there appear to be no market timers (no matter how much they learn or know or do) who stand out as superior investors.

After waiting ten years to win his bet, Buffett was quick to make his point: that it’s nearly always better to “stick with easy decisions and eschew activity.” Investing is unique in the sense that even experts and senior economists seem to be incapable of beating the market indices on a regular or reliable basis. In just about every other activity—tennis, golf, physics, surgery—an expert will be demonstrably better than an amateur. But no reputable “expert” in the investment world will ever tell you that he or she can consistently beat the market on your behalf. In fact, any guarantees of superiority are forbidden by the regulators. How many other careers is that true for?

Finally, investing is a bit strange because, with your portfolio, there are many times when (unlike most human activities) the best thing to do is to do nothing. And there are many times when (unlike just about every other human activity) it’s actually quite difficult to do nothing.

None of this means that expertise is useless when it comes to managing portfolios. A professionally-managed portfolio will use a variety of other ways to boost the total return. Professionals have access to quality low-cost investments, which can, in some circumstances, save a lot of money in annual fees. Professionals get in the habit of keeping some of your money out of Uncle Sam’s pocket by harvesting tax losses and avoiding short-term capital gains. By creating a diversified mix of investments, an investment professional can create situations where the stock market is going crazy on the downside, but other investments are holding their own and cushioning the blow.

In every field, true experts understand humility. In the investment markets, as the Buffett experiment has shown us, nobody really knows when or how the markets will bounce back or settle down after manic moves in either direction. This bit of wisdom won’t get anybody a rate of return higher than the markets are giving out. But it does help prevent people from making expensive mistakes during those times when it’s so very very hard to do nothing.