Money, it's a hit

Time is not money nor is money time, but often we sacrifice one to enjoy the other. They are in a word resources.

Like all resources, the greater and seemingly unlimited their availability to us, the lesser their value to us and the less likely we are to consider how they're being used... and so the opposite is true as well.

This is the adult perspective. Money then becomes representative of the time we exchange in acquiring it and so the waste of money is also the waste of time.

However time is the resource of infinite measure to a child and so too money (both acquiring it and the concept of it) bares little consequence in how it is spent.

This is why children cannot grasp the concept of those who are upset that they waste either. 

To them it is both perplexing and pointless that adults should be so concerned about how either is spent.

Give it time, they'll come around.