If your opponent is rich, they can hire an army of lawyers, and you'll generally need a correspondingly huge law firm prepared to invest their own time and money in countering that. The kind of law firms we're talking about are both few in number, and generally fully-engaged by well-paying clients -- clients like your rich opponent. The incentive to take on a case like this is pretty limited.
When you're dealing with lying buggers though, it represents an option to sue. Insurance is similar.