Wealth lasts for generations, and you don't pay inheritance taxes on family connections or a top tier education. New taxes that make the accumulation of wealth more equal, i.e. progressive income taxes or capital gains as income taxes, will not erode the existing wealth disparity within our lifetimes. Just look at how the policies up until the 80s resulted in white Americans owning all the property, which subsequently appreciated due to monetary policy.
If wealth inequality is a problem, which I believe it is, you should tax wealth because it directly reduces the gap in absolute terms.