I'm all with you for the first two paragraphs. In the third, I think you're making the potential problem seem worse by failing to acknowledge that there would

I'm all with you for the first two paragraphs. In the third, I think you're making the potential problem seem worse by failing to acknowledge that there would be many currencies, so a failure would be contained. In the fourth, you're showing the reasons for your own error: "huge problems with monopolies: the banks": each of the "monopolies" you cite, you do so in the plural. "Banks" clearly can not be a monopoly, as there are many of them. I think what you're getting at is the "too big to fail" rhetoric?