$10M isn't a "cave," it is a reasonable settlement.
$10M sounds like a reasonable amount to you because being smarter than the average Prosper investor, you only lost less than $100. The stoopid people like me, that lost a heck of a lot more, are really concerned there will not be enough money in the $10M pot to make us even close to whole.
That is completely irrelevant, for several reasons. The biggest probably being that of course $10M won't make the big losers close to whole. But the class action only addressed one of Prosper's many shortcomings -- it's failure to register its securities before selling them. Had it done so, total losses would have been less, but they wouldn't have been zero -- there are many reasons why lenders lost money on Prosper, so it isn't reasonable to expect to be made whole from this lawsuit.
Moreover, it also isn't reasonable to expect ANY settlement (without a substantial possibility of large punitive damages, which isn't an issue in this case) to make lenders whole or close to it (i.e., recoup all aggregate lender losses), because that would be the maximum possible amount that Prosper could lose if it took the case to trial and lost, assuming everything went well for the plaintiffs. But by definition, a settlement is a compromise. It always falls somewhere between the best case plaintiff scenario and the best case defense scenario. Here, it is possible that had the case gone to trial, plaintiffs would have lost. Or even if they won, they may not have won enough to cover all lender losses. And even if they did, the case could be tied up on appeal for many years, during which time plaintiffs would get nothing. Or perhaps Prosper would go BK and plaintiffs would get little or nothing. All of that has to be factored into the settlement calculation. Since Prosper's maximum exposure was about $40M is I remember correctly, the settlement is 25%, paid relatively quickly. That is a very good settlement as these things go. A common class action settlement involves near worthless compensation to the class, such as the infamous "coupon" settlements, and even a cash settlement is often 10% or less of the possible judgment amount. So 25% is quite good.