Who cares what his parents spent in taxes in accumulating the wealth, he is not his parents. He should be taxed on this "gift" that suddenly goes from a 14k threshold to an 11mil threshold because someone in his family died, and he should be incentivized to work in the economy like everyone else with significantly reduced income taxes on earned income, in order to contribute to higher GDP for the country.
Sitting around playing xbox and ordering pizzas in the air conditioning all day with mommy and daddy's money does not contribute to the economy and increase the country's GDP and reduce the trade deficit like Trump continuously brought up in his 2016 debates.