[jvz]

Even in a (totally unrealistic) scenario where N dollars are "useless" to you, but N+1 get you something of great value, it's not true that the (N+1)th dollar has greater marginal utility than any of the other N dollars, because you need all those other dollars to buy the thing. In other words, the previous N dollars weren't actually useless: they enabled you to obtain the (N+1)th dollar. Without them, that (N+1)th dollar is just your first dollar.

[TeMPOraL]

Sometimes there's a psychological difference though. Say you have $8 in your pocket, and there's a movie you like to see in the cinema nearby. The ticket costs $10. You know you won't get that $2 in a reasonable timeframe - maybe it's your only evening off, so even if you get some more cash tomorrow you won't have a chance to see the movie. Maybe you also don't feel like begging strangers for change. In this situation, you may find yourself wishing for those $2 very much, and after realizing you can't get them, you'll say "fuck it, I may as well spend my $8 on some pizza or beer" and then do so.

Maybe that last $2 don't have greater marginal value than the $8 in your pocket, but that $8 loses its perceived value the moment you realize you won't get additional $2 in time.

It's not a hypothetical situation, by the way. I've been in those several times in the past, and followed exactly the same pattern of emotional reasoning.

[pc86]

Probably OT, but all things being equal the person that saves the $8 until next week's night off will probably end up in a better place in life than the person that gets a slice of pizza and a beer.