Is there an economic theory of why people like to hold on to wealth? It seems to me that many people work to become wealthy, but not because they want to consume all that wealth. Many people give it away, other's don't, but still they do not spend it. You hear about some rich 40-year old's throwing money away, but you seldom hear of a rich 80-year-old throwing anything away! What is the economic theory for "scrooge"? Are there simple preferences that make this the right strategy? 
(I head somebody say that JP Morgan used to say it was a way of keeping score. Is there a theory of this?)
You could consider unspent money to be a call option. The set of future investment opportunities is unknown, so if you're optimistic about future opportunities it could be a valuable call option.

So saving money can be a profit/preference-maximizing behavior.