But it is also the only regressive tax we have, as all income over a certain amount is untaxed. So it ends up being a really complicated curve of who gets what

But it is also the only regressive tax we have, as all income over a certain amount is untaxed. So it ends up being a really complicated curve of who gets what return on their money, so the super rich and the super poor get the best deal, while the middle class gets hosed.