With which part ? That there are millions of crooks, or that every rabbi should learn how to deal with them ?
There aren't as many crooks as you think there are.
It's the police job's to deal with them, not a Rabbi.
A Rabbi isn't required to do anything. If anything, you can advise communities to hire rabbis with those capabilities.
A rabbis purpose in a residential neighborhood is to deal with household questions, not business/financial questions. Just like a bank in a residential neighborhood isn't going to give you a billion dollar line of credit.
Furthermore as 'sport' said, a Rebbi is anyone you learn torah from and look up to. If you're luck you'll be able to seek his advice on any subject. That doesn't mean he's a 'Rabbi'.