So why do they do it at all? Harvey Levin has a one-word answer: "Ego." He says, "I think that a lot of celebrities make the mistake of trying to manage their image so much, that if someone says something off-kilter, it just sets them off."
And beyond uncontrolled ego, there might be some very controlled publicity. "Honestly, the biggest fear that celebrities have is becoming irrelevant," says Levin. "Nobody wants to become a Gabor sister."
The Gabor sisters, says Levin, "used to be really hot and really famous, and people wrote about them a lot, and the suddenly, it's like 'who cares,' and that is the worst thing for a celebrity to hear."
Maybe just maybe, celebrities can stay relevant, stay in the news, by fighting.
"I think people recognize that people like Rosie O'Donnell, like Donald Trump, are very shrewd about publicity," says Eric Dezenhall, a crisis management consultant. "The endgame of whatever they do is often to get on TV."
But sometimes, in the craven drive to stay relevant, there is a risk. Ratings for the premiere of Donald Trump's show, "The Apprentice," when measured in total viewers, were down from year ago. Perhaps you can go too far.
"I think these celebrity battles serve to remind people how little in common celebrities have with the rest of us," warns Dezenhall. "They operate in a totally different galaxy, and it ultimately doesn't make them look good. But it is entertaining for us to be reminded from time to time that they live on another planet."
Maybe the ultimate social commentary was provided this week by World Wrestling Entertainment, which staged a bout between a fake Rosie O'Donnell and a fake Donald Trump. It's true that a celebrity might want to avoid becoming a Gabor sister, but on the other hand, what celebrity wants that?