Thank you for your comment @motoengineer.
What makes the USD better than the JPY? Or the Euro?
People use what they have. Manna is given to anyone who signs up and verifies. The token's value rises as the number of people with the token increase as well as those who use it.
Based upon your conclusion, no cryptocurrency has much value since there is very little usage, as of now, with any of them.
One big difference between Manna and other currencies is that we are putting it directly into the hands of poor people. Every other currency requires buying in or doing something for it.
So suppose you give it to poor people, amount the poor, they would accept it and trade it for inter poor people services (that's really rude way of putting it, but you get the point). That creates its own closed economy, but money flows from the poor people from volume.... I could see that.