The man is wealthy, quite wealthy, but not that wealthy.
Hold that thought. Wasn't he living an outrageously extravagant life? Yes, he had enough for an extravagant life, but not enough money to get through his trial solvent or not imprisoned.
http://www.creators.com/liberal/alexander-cockburn/dsk-is-the-fix-in.html
His wife is the wealthy one, while he himself has mostly been just a very well paid person, but not exceedingly rich. Neither has enough funds together to find a good lawyer who is willing to represent them, or enough to avoid a prison sentence.
How can a man of such a powerful position and an international status squander it all so needlessly? 10 years from now, DSK will probably be living in a modest apartment in Paris, totally out of the scene, long forgotten, and back down to a modest life of a simple university professor. It will be like Guy de Maupassant's The Necklace, but with a fall from a greater height.
The reason may be more complicated than that. His wife is apparently fed up with him, so much she only puts on her wedding ring only when in court. Lose your family fortune to cover up a known degenerate? I don't think so. In fact the only reason she still hasn't dumped the scumbag is because she's been "strongly pressured" by the champagne drinking, chaffeur driven limo riding, Socialism-adoring French elite. President Sarkozy himself, a man whose cabinet has been crippled by sexual "scandals" and who isn't a stranger to pecadillos, was apparently very vocal in insisting she "stands by her man". Gotta love these politicians when they talk about "family values"!
I am pretty sure Anne Sinclair, who is a bit more shrewd than your average heiress than she wants to show, has already drawn a line. After that line is crossed, it's over. Strauss-Kahn won't get a penny more. It's also comical to observe how the SocialistPparty, of which Strauss-Kahn is a leading member, hasn't so far lifted so much as a finger to help him. Apparently solidarity only works when it involves taking money by force from taxpayers who cannot defend themselves. When you have to use your own money... no thanks.