I think what I'm kind of struggling with is the "unlimited wants" phrasing? I mean, realistically, even if I had the net worth of Warren Buffet, I wouldn't be capable of spending all of it -- doesn't that mean there is a limit to my "wants"? Or is that issue avoided because leisure time is a "want"?
Warren Buffet could write a check tomorrow to some charity and spend every last dollar. In fact, he has already initiated that process. He has been very open about the fact that after he and wife die, his descendants will receive very little.
It is always possible to spend all the money.
But remember this while reading your economics textbook. In economics, the consumer makes perfectly rational decisions in order to maximize their "utility" (which is like happiness - except not, because in economics, consumers don't make decisions based on feelings. So it's more like maximizing your spending potential with robotic efficiency).
Don't mistake consumers with real people, like yourself. When you find yourself saying, "But that's not really what people do/think/act..." remember that they aren't real people. Economic theory doesn't concern itself with individual behavior in the truest sense - that's what psychology is for.
Consumers are Theoretical Robot People. When they see money, they see its potential. They are always using it or planning to use it for something. They never leave money idle.
Gah! Then what's the point of all of this mumbo jumbo, if it's not even about real things?! Well, as it turns out, when consumer behavior is taken as a whole - when we're all averaged out - what we do really does closely resemble the behavior of an army of Robot Consumers.