Money is valuable for "reservation demand". The more people want to hold it, the more useful it is to everyone. Only this way it can become a currency. You can't have currency without value and can't have value without holding and having many hands to hold.

http://blog.oleganza.com/post/66953255676/transactional-curr...

http://blog.oleganza.com/post/43378777734/on-circulation-of-...