It's not a punishment, even if you tax a millionaire at 90% they still have $100,000 income and that's more than enough to live very comfortably, and nobody's suggesting a rate of 90%. And there are people a LOT richer than $1,000,000 a year. People simply don't need that kind of money and there are plenty of people who DO need it. I'm not suggesting making everyone completely equal because I agree that's stupid. I just think it's a given that current tax rates aren't enough and it makes more sense to take from those who have than those who don't. Obviously it's not an OPTIMAL situation but that's how it is.
I think that part of the freedom that our country was founded on would be at stake. Sure they may not need the money to survive. But they sure do need it to do all sorts of useless crap. But since they earned it, they should have the right to do that useless crap.
I don't think it's really a matter of what would be best. It's a matter of respecting the rights of people, no matter how rich or poor they are.