I hope you remember the collapse of Lehman Brothers in September 2008. It was the one the US decided should be allowed to go to the wall as an example to the others. We got a world financial crisis from which we have not recovered as a result.
The logic error was simple. It was big, but no so big. And it was one bank, and each bank was different.
How wrong could you get? There is no one bank. There's a banking system and each of the bigger players is intimately related to each other in the system in a web few can, could or will ever understand at a point in time. Pulling the plug on Lehman broke the web.
And it's the same with Greece. Sure it's a mess. And there are bruised egos around a table.
But there is also a bruised people.
And there is here another web that could be broken in ways that no one can be sure about.
Suddenly the world seems to be embracing Grexit. Think next world financial crisis. I could be wrong. But the precedents aren't good.