This is comical. Anyone who tells you that currency was actually worth $300MM is out of their mind. This is an interesting experiment, but seems more like a pump-and-dump.
True value or Real Value are stabilized values in the market directly proportional to usefulness of the commodity or currency. If people wanted this much ETH, it would be worth that much, but saturating the market with that much more ETH would drive prices down. It's like the meteor that was made of Iron that swung by the earth "it's 5 quintillion dollars of iron ore!" well, with simple multiplication that may be so, but the assumption is that this material would be absorbed into an economy that can use it effectively. Nobody is actually going to hand you 5 quintillion dollars for the meteor.