I have had many discussions about income tax rates with friends and fellow acquaintances from my university. The overwhelming majority are in favor of a really high top marginal rate. Their reasons boil down to:
1. The rich can afford to pay the high tax rate. It won't hurt them to part with an extra million dollars from their fat bank accounts. Such statements are usually made with a hint of a sneer.
2. Most rich people haven't earned their wealth, they were born into it. It's not fair for them to keep all of "their" money.
3. The poor "need" the money. It's only compassionate to follow the sage advice, "from each according to his ability, to each according to his need".
Reason #3 is somewhat amusing. Why? These are university students who're dependent on their parents, knee-high in debt and yet they define compassion as voting for the extreme left-wing party, so that someone else is forced to pay for the welfare state.
I've never understood the point of having different income tax rates. A high-income earner will have to pay more money to the government than a low-income person if there was a single rate. So, why punish the well-off with higher rates?
It seems that the answer isn't rational. No wonder, the first two reasons are the most popular.