The litigators file on behalf of shareholders and creditors and employees - all of who have been hurt - financially or otherwise, by the reckless and criminal actions of the company and its management. they collect from the damages paid by the company if guilt is proven.

second, bankruptcy does not mean there's nothing left to take ... Lehman had $ 639 BILLION in assets... those are probably worth some 350 billion in a distress sale, but that's not small change either.

finally, if you sue directors for malfeasance, their insurance company pays... so there's lots of sources where that money can come from
(unless their D&O insurance was provided by AIG, and if you haven't filed by this weekend, THEN you are up sh1tcreek without a paddle )