You've got it exactly backwards. The problem isn't that the rich buy too much. The problem is that they don't buy enough. They lend and invest and leverage and otherwise use their money to create debts owed to them.

The cars they buy each pay autoworker wages. The shares they buy in that car company creates an obligation on the company to pay them dividends.

We should be doing everything we can to increase their costs and decrease returns on excessive investments, while removing impediments on them buying services and manufactured products.