Warren Buffett has been a consistently successful investor for an astonishing seven decades. You might think the reason for his company's impressive returns is the thorough research he does before investing. Or the fact that he consistently takes the long view, betting on companies that have long-term potential for high earnings. And you'd be right--those are both big reasons for Buffett's success.

But he also has a character trait that has helped him stay on top in a rapidly changing world, and it's not one most business leaders value--he's willing to be wrong. In addition, he's willing to admit he's been wrong, something few leaders ever do. What's even more important and more rare is that he's willing to rewrite his own rules--even rules that helped him succeed in the past--to adapt to changing times and new realities.

Case in point: Apple. Berkshire Hathaway revealed this year that its single biggest investment is in Apple. Berkshire owns just over 5 percent of Apple, which makes up more than 40 percent of its U.S. stock portfolio. Buffett's been investing in the company for a few years now, which is interesting if you remember that for decades, the Oracle of Omaha famously avoided technology stocks. In fact, that was Rule Number 5 of Berkshire Hathaway's acquisition criteria: "Simple businesses (if there's lots of technology, we won't understand it)."

About a decade ago, Buffett changed his mind about technology and began investing in IBM. At the time, it was the most long-established and stable-seeming tech company he could have picked. He said he was impressed with the hold IBM appeared to have on its customers because switching IT providers would be challenging for most companies. "There is a lot of continuity to it."

Buffett was wrong. He didn't foresee how the relentless growth of cloud computing would change everything, loosening IBM's grip on its customers and upending every aspect of tech. Buffett invested in IBM for about seven years, selling all his stake by 2018. He managed to follow his famous Rule Number 1 and Rule Number 2 of investing--both of which amount to "never lose money"--but he didn't really make any, either. Even investing in government bonds would have yielded higher returns. It was a rare big mistake for Buffett.

Apple's high profit margins.

This is where someone less wise might have said, "See? I was right all along. We shouldn't invest in tech companies." Instead, Buffett concluded that he had chosen the wrong tech company and began investing in Apple. He noted that it was a high-margin company--able to bring in huge returns in proportion to the assets it holds--and one of the few that could keep those high returns going over time. "If you look at Apple, I think it earns almost twice as much as the second most profitable company in the United States," Buffett told CNBC in 2018.

What I find amazing about this story is that, without a lot of fanfare, Buffett rewrote his rules for how to be a successful investor. He went from we don't invest in tech companies because we don't understand them to we do invest in tech companies because some of them have very high margins and that's the way to make the most money. 

Most of us, once we find a formula that brings us success, will stick with it through thick and thin, even when the formula stops working. It takes wisdom, humility, and a great deal of smarts to abandon a rule that's served us well in the past. We have to be able to say, "That thing I told you was an absolute necessity for success? Never mind." That can be painful to say, and yet, as Buffett knows, in a quickly changing world, it's something we all need to be able to do.

So next time you're sticking to a hard-and-fast rule that you use to make decisions about your own business, ask yourself whether you're following the rule because it worked well for you in the past or because it's working well for you right now. Or just ask yourself what Warren Buffett would do.