Would Sun Tzu have settled?
Only if the settlement could be leveraged to improve his position in a larger conflict. Hmmm, I guess I can see why the lawyers would want to settle, but not the plaintiffs.
You can't see why the plaintiffs would want to settle? How about:
1) Litigation is uncertain -- it is possible that the plaintiffs could lose at trial, meaning they get nothing (versus say around $5M in the settlement)
2) Or even if plaintiffs prevail at trial, Prosper would appeal, which would take around two years. If Prosper won on appeal, Plaintiffs might get nothing (see #1), or the case could be set for a new trial. Which might take another year, and would be followed by another appeal (about 2 more years). If Prosper lost on appeal, it could petition the CA Supreme Court for review. If granted, that would likely take about another two years.
3) Prosper has yet to turn a profit; indeed, it's losses generally keep growing. There is a high likelihood that Prosper will eventually go BK. If it does, the plaintiffs' claims will likely be extinguished, and plaintiffs will get nothing. The longer the case drags on, the more likely such an outcome is. Moreover, if plaintiffs succeeded wildly at trial -- say a $40M judgment -- that would almost certainly result in a Prosper BK. So there isn't a whole lot of upside for the plaintiffs to go to trial -- maybe Plaintiffs get $15M, or $20M, and maybe that isn't enough to throw Prosper into BK, although it would be many years before plaintiffs saw any of that money. Under the settlement, the money will start to flow soon.