As income goes up the amount spent on necessities flattens out. You only need so much toilet paper but you need exactly as much as you need, for example.
"Necessities" are variable. Are you talking about what one person "needs" or are you talking a breadwinner in the family, supporting a family of four, or five, or three...whatever.
And who's to say how much goes back into the economy, is spent on business related items, ect...? The variables into this equation are endless.
No one has the right to tell someone how they must or must not spend their earned income. The whole idea is absurd.
Of course, not in the mind of a liberal, telling someone else how to spend their income, I'm sure you'll agree ;)