Here’s something that you probably understand completely: Success in one aspect of business (or life) does not automatically guarantee success in another. In other words, just because you are great at one thing doesn’t mean you’ll be great if you try something else.

Most regular people understand this intuitively, but for some reason, a lot of successful business executives seem to be delusional about this. Here’s this week’s example: Sears chairman Edward Lampert.

Lampert made a lot of money—billions, according to The Wall Street Journal—from managing hedge funds. Clearly, he’s very, very good at that, and the huge pile of money he made doing it is the ultimate measure of his success. But this makes me wonder: As successful as Lampert has clearly been as a hedge fund manager, how does this in any way qualify him to manage a large, complex business such as Sears?

It doesn’t, of course, and this week’s news proves that. As The New York Times so cheekily put it, “Edward S. Lampert has a new strategy for Sears: less Edward S. Lampert.”

Three years ago, Lampert put together a deal that merged Kmart and Sears into a new company called Sears Holdings Corp. that was controlled by Lampert. He installed himself as chairman and personally jumped in managing the company. Unfortunately, Lampert has no background (or discernible skills) in retailing or marketing, and he’s a micromanager to boot. The results have not been pretty, and the price of Sears’ stock has tumbled from around $200 a share in April 2007 to a little over $100 today.

So Lampert does what a lot of arrogant executives do when confronted with their own shortcomings—he fired someone else. Earlier this week, Lampert canned Sears’ CEO. He said he would find a new chief executive, although as one analyst told the Times, “Sears will have a very tough time filling this job.” That’s because “Sears Holdings has earned a reputation for starving its stores of money, anathema to experienced retailers. The company is in trouble. And Lampert has already clashed with—and tossed out—several executives.”

Now that Lampert has been hammered by Wall Street, he’s had a change of heart and tells the Journal that he’ll step back and allow managers running individual businesses to make their own decisions rather than relying on corporate bosses to make the big calls. “He compares Sears with Warren Buffett’s Berkshire Hathaway Inc., in which managers are given a long leash to run businesses, and Buffett doesn’t get involved in their day-to-day operations.”

Lampert may want to be like Warren Buffett, but does he really believe he can suddenly change his micromanaging ways and become more like Buffett, a great manager and one of the world’s greatest investors? I don’t think this is possible because Lampert probably doesn’t understand that what made him highly successful as a hedge fund manager just won’t work when trying to turn around a huge retail operation.

Great managers and leaders—like Warren Buffett—become great because they know in their hearts that they don’t know everything. They put great people who know what they are doing in charge and then they get out of the way.

Can Lampert subjugate his massive ego long enough to let someone else take charge of Sears Holdings and show him the way? Only if he can unlearn everything he thinks he knows. And that’s a tall order for anyone, let alone a billionaire.