And the poor are more likely to put pretty much all their income back into the economy in their day-to-day living, whereas the rich don't.
I'm aware of the velocity of money and the perception that poor people pour money back into the economy rapidly while rich people don't (and it matches my personal biases, so I like the idea a lot) but -- I'm trying to figure out what the rich can do with money that actually takes it out of the economy. Unless they actually stick dollars in suitcases and store them in the wine cellar, almost anything else I can think of puts the money in someone else's pocket one way or another. Stuck in banks: used to back bank loans. Buying ferraris and Monets: money has gone to the previous owner. Investments, likewise. Taking money out of the country probably counts from a single country's economy standpoint, but not from a global standpoint. I'd be interested in hearing other people's thoughts on this.