That's a good point. And makes me think of videogames analogy, particularly MMORPG.
In a typical MMO, you need to labor to earn money (known as "grinding") to buy all the stuff you'll need to make progress easier (and/or possible). But at any time, you can just stop, take time off, go explore the places you've been to (i.e. not containing enemies stronger than you can beat), or even just log out and leave your character be for a week. You lose nothing except time and perhaps your rank in some completely optional competition with other players. But your character won't go hungry, won't starve or freeze to death, won't be evicted for not paying taxes.
That illustrates the difference between money being useful, versus being necessary. And even if it's only useful and not necessary, that doesn't mean you won't be motivated to earn it - you will want more money if the things you can buy with it are interesting enough.
In broad strokes, I'm more capitalist than communist, so I don't really disagree with the whole "greed is good" thing. Where I part ways is the unstated - often, I suspect, un-recognized - premise that it's the only good. Money's only useful for what it can buy, and its value has been artificially inflated by a social structure that makes it something that you just can't live without.