I, for one, can't think of any good reason.
For anyone who is unaware, Donald Trump recently sued comedian Bill Maher for breach of contract because Maher publicly offered to donate $5 million to Trump's charity of choice (he suggested the "Hair Club for Men") if Trump could prove that he was not the offspring of an orangutan. Obviously, by making this "offer," Maher was parodying Trump's offer to donate $5 miilion to charity if President Obama released his collegiate records.
Trump then produced his birth certificate, demonstrating he was in fact the son of Fred Trump, and demanded $5 million. When Maher ignored Trump's letter (which was sent through Trump's counsel), Trump sued.
I'm not surprised that Trump brought the lawsuit. All right, maybe I'm a bit surprised. But the reason is different than you might think. Given the laws on the books about frivolous lawsuits, I am sorry to see that there was an attorney who was willing to lend his name to such an absurd lawsuit.
I'm not a big Bill Maher fan, but his comment that the legal system "is not a toy for rich idiots to play with" is dead nuts on. I, for one, am hoping that the judge on the case uses the opportunity to teach both Trump and his attorney a lesson about the costs of engaging in frivolous lawsuits, because these types of cases delay other righteous lawsuits from coming to fruition, and tarnish the legal system's reputation as being overly indulgent.