Two points to add:

1. You mentioned RICO in passing. A victim who pays back a Mob loanshark by busting out his business, or through a "giveup," can be considered a conspirator in a "Racketeer Influenced Corrupt Organization, and could face the same double digit sentence as his Mob victimizers. That would provide a Grade-A incentive for the victim to cooperate with law enforcement--a big risk to the loanshark and his higher-ups.

2. Some states permit "payday loans" carrying interest rates far above Mob vig. And, it's totally legal.