No one puts the activist in "activist investor" quite like Carl Icahn, who just won the latest round in the fight over Dell computers—just one of his many, many attempts to bend major corporations to his will. Icahn is currently trying to block the proposed leveraged buyout of the personal computer manufacturer, because he believes the $24.4-billion asking price to buy it back from stockholders isn't high enough. On Monday, Dell agreed to let Icahn take a private look at their books, after he threatened to lead a shareholder revolt to prevent the company from going private.

And this isn't even Icahn's biggest fight at the moment. He's also in a very personal war over the supplement maker Herbalife, risking a billion dollars worth of his own wealth and reputation to keep a rival investor from destroying the company. There's also Netflix, Transocean, Navistar, Yahoo, and the boards of dozens of other companies who have found themselves at war with him, because he didn't like the way they ran their outfits or he saw an excellent-money making opportunity. Which is often the same thing. When you keep on bullying, the bullies win.

The Wall Street Journal calculates that Icahn has started 68 fights with companies that he's invested in the last 10 years. That includes 28 shareholder proxy battles, most of which he has won. (Or at least, didn't lose. Most of those resulted in some kind of settlement.) And his tendency to fight hard for what he wants has only increased as he gotten older. Eleven of those activist filings happened just last year, and he's already started three in 2013. Let's just say he's not going quietly into retirement.

Icahn doesn't have clients anymore, so he's only doing business with his own personal fortune. (At $20 billion, that's a considerable fortune.) That also means he doesn't have to please anyone but himself, and that when he does wade into a fight, it gets very personal, very quickly. He basically called Bill Ackman—a self-made billionaire, remember—a lousy investor and a cry baby. It's not about the money. It's about his money.

There's no question that Icahn has earned the right to push corporations around. He's not right every time, but he's won enough—and made enough people very rich—that no one can afford to ignore him. He could never place another bet and go down as a finance legend. So what make a 77-year-old billionaire spend all his time arguing over stock prices and proxy votes? He does it because he can... and he's good at it. As another fellow investor told Bloomberg's Katherine Burton, to Icahn, "This is sport. He’s got time on his hands and money to make."