I can't take time today to reply at length to Proof Reader and others about taxes, but here's a start.
There are moral reasons, religious reasons, reasons based on the needs of the majority of the people, historical reasons and political reasons for solving this economic disaster by taking back the money of the very wealthy through some kind of massive redistribution. However, all of these reasons can be answered; they all depend on your perspective, what you care about, who you care about and what your values and beliefs are.
However there is another dimension of this argument - the consequences of the two views, and whether we are willing to live with them.
What I will argue is that the state of affairs we have reached now is caused by rapidly growing extreme inequality, which is unsustainable and has led inevitably to a massive economic crisis and meltdown, a crisis which is far from done. And that - whatever your beliefs and values - this path leads to disaster for us all.
After looking long and hard at the logic of this conclusion and the economic data supporting it, you may have to conclude that wealth redistribution is a practical necessity, and progressive taxation is the most orderly, least disruptive, least dangerous - and least revolutionary - way of accomplishing it.
This may require readjusting your values, beliefs and commitments.
Some of us, faced with a moment like this, retreat and take a "facts be d* * * *d" attitude. We humans however have a remarkable capacity for rationalizing necessity, so I remain hopeful.