When they spend the money, the goods they're consuming or moving around are displaced from where they would have been. Spending the money doesn't create goods o

When they spend the money, the goods they're consuming or moving around are displaced from where they would have been. Spending the money doesn't create goods out of thin air. So unless they are making an investment that is a good one that somehow no one else knows about, it doesn't really impoverish society for them to sit on it. This argument, of course, applies on the margin and does not apply to every bit of wealth in the system.