Answer
Anyone using or holding money is being taxed, albeit indirectly, because inflation depreciates the value of their money.
Work Step by Step
Put simply, when money increases in circulation, each "unit" of money decreases in value.
As with most things, the scarcer a resource is, the more it is worth. Money is no different.
Those using or holding money are being taxed because they are shouldering the burden of value depreciation.