in looking at his "fair share" it doesn't matter how many people it would account for if it were divided up equally among every person in the U.S. What matters is how large his income is in relation to the incomes of the rest of the people in the U.S.
given that his income is so much exponentially larger than the normal person, of course he should be paying taxes that amount to X number of "regular" people's tax bill.
193 normal people's tax bills added up is still jack shit compared to the taxes a millionaire should owe. It's not about the dollar amount that the millionaire pays, that's not important here, it's about the Percentage of Income that each person pays.
If someone who makes 100,000 a year has to pay 20% (for simplicity sake) that amounts to 20,000 in taxes.
If a millionaire who makes 2,000,000 also pays 20%, it comes out to 400,000 a year. Each person's overall income, and more importantly Disposable Income, is reduced by the same factor: 20% or 1/5 in our example here. That's fair. Each person is impacted equally.