Here's an interesting editorial by Warren Buffet. You have to admire his honesty: "Last year my federal tax bill - the income tax I paid, as well as payroll taxes paid by me and on my behalf - was $6,938,744. That sounds like a lot of money. But what I paid was only 17.4 percent of my taxable income - and that’s actually a lower percentage than was paid by any of the other 20 people in our office. Their tax burdens ranged from 33 percent to 41 percent and averaged 36 percent. "
Here's our basic mistake: "If you make money with money, [..] your percentage may be a bit lower than mine. But if you earn money from a job, your percentage will surely exceed mine - most likely by a lot". If you want to make money, you have to find a way to stop selling your labour at an hourly rate.
Here's the full article.

As a side note, I'm sure a lot of his super-rich buddies are fine with paying low taxes and don't necessarily support his opinion.