The biggest advantage of a private, closed economy is definitely protection from a suffering global economy.
Every time that a country important for global trade experiences an economic crisis, all other countries are impacted too. A nation crisis quickly becomes a global one. But if a country doesn't trade, there is no influence, positive or negative from the global economy. This is a great advantage, especially during times of global economic instability. And I think that we're in those times now.
Why should a small country suffer economically because a few banks in a bigger country went bankrupt? It doesn't make sense.