The roughly 1/3 of tax filers who pay no income tax are not well served by the economy.

Those who fall into the top marginal rate category have shelters to reduce the amount of tax payable and the higher the income the greater the opportunity..

The usual argument against taxing the wealthy is twofold, reduced incentive and the revenue gained would not slay the debt.  It is not unreasonable to assume that excessive incentives encourage reckless behaviour and are destructive to the economy.  

Peter Drucker amongst others thought that incomes exceeding 20x the average would be inimical to capitalism.  Since the median tax filer earns roughly $30,000- this would translate into a maximum level of $600,000- for top earners which is not unreasonable.

It can also be argued that excessive income weakens democracy through the buying of influence.  Reducing the income gap, not increasing it, should be the aim of taxation policy.