In an attempt to convince us to vote for Hillary Clinton rather than Donald Trump, Michael Bloomberg, a former Mayor of New York City,  claimed to be an expert in identifying con artists. At the Democratic convention he told the audience (video here):

"I'm a New Yorker, and I know a con when I see one."

Why are people in New York City experts on swindles and deception? Can you figure it out?

Here is a hint:

When Michael Bloomberg was mayor, he helped Silverstein commit insurance fraud. In 2006 he send letters to the insurance companies to pressure them into paying Silverstein. The original news article has been deleted, but it is in the Internet archive here.