Today Ben Bernanke added his voice to those who are worried about Europe’s debt crisis.

But why exactly should America be so concerned? Yes, we export to Europe – but those exports aren’t going to dry up. And in any event, they’re tiny compared to the size of the U.S. economy.

If you want the real reason, follow the money. A Greek (or Irish or Spanish or Italian or Portugese) default would have roughly the same effect on our financial system as the implosion of Lehman Brothers in 2008.

In other words, Greece isn’t the real problem. Nor is Ireland, Italy, Portugal, or Spain. The real problem is the financial system — centered on Wall Street. And we still haven’t solved it.