But I'm saying that the only reason they can spend this extra money is because they were granted a tax cut.
No. I'm afraid I must disagree in the strongest terms possible. The reason they can spend this 'extra' money is because they earned it, not because they were granted anything. Wealth does not come from the government.

A luxury tax is a consumption based tax, and we are discussing an income based tax.
Money was taken away from rich people by the government. This is a tax on the rich.