Since JP Morgan is the one backing the coins with USD, and controlling who mines, they can do whatever they want to fix errors or crime. If something goes wrong they can just mark the "bad" coins as tainted and refuse to exchange them for USD and give you new coins to fix the problem.
Paper money was created because it was more convenient than lugging around precious metals, this is just the same. It has no value on the market by itself, it's just a way for a bank to account for stored value.
Paper money was created because it was more convenient than lugging around precious metals, this is just the same. It has no value on the market by itself, it's just a way for a bank to account for stored value.