I am not defending Cosby. He probably is guilty of some of this. But this is also about a man reputedly worth 400 million. Ignore this at your peril.
It is certainly possible that some of the women are hoping for a financial payoff. However, since the statute of limitations has long expired (except for one case where it may still be active on a technicality), it is difficult to see how that could be a motivation.
It is in my view highly unlikely that some twenty women who did not know each other spontaneously decided to go public about the same kind of traumatic assault with accounts that were frighteningly similar, revealing a cunning modus operandi.