[copperx]

Your logic is faulty.

Using your reasoning, sales and property taxes are also progressive, because wealthy people purchase significantly more goods and properties, which are frequently more expensive than a middle class person would buy. Thus, the rich end up paying more taxes.

[alexmingoia]

Using my logic, tax assessments that don’t change based on income are regressive, and tax assessments that do are progressive. It’s not complicated, and it’s a widely used definition.

https://en.m.wikipedia.org/wiki/Progressive_tax

You may think a flat income tax rate isn’t progressive enough, but it’s not a regressive tax.