I kinda think (under OUR economic system, supposedly of opportunity) that ALL benefits should be means tested.
Ergo. IF you prospered so well under our Laws and freedoms as to have a genuine excess then you should be willing to forego SOME of your benefits to the overall fund (those that paid in less than they collect).
As to any Federal Income Tax rate. THAT should be just low enough to fund the Gov't BUT make OUR Representatives actually do their jobs and make choices sanely as to HOW to spend the tax dollars!
AND, once the budget is balanced (as it WAS under Clinton!) and we can start paying down the National debt THEN the rate could ostensibly be LOWERED!