Warren Buffett thinks his taxes should be higher. An understandable response is, "so, pay more in taxes, Mr. Buffett." Some conservatives, in fact, call Buffett a hypocrite for not voluntarily paying a higher rate than his secretary.
Here's an analogous situation:
Michele Bachman's husband runs a health clinic that bills Medicaid, while she generally rails against big government. Liberals (imagining she would abolish Medicaid, I guess) sniff out some hypocrisy here.
If we can set aside peripheral questions and posit that Bachman does, indeed, want to cut or abolish Medicaid, we can say these situations are analogous. And neither is hypocritical. In fact, both are noble, principled, stands that deserve praise.
Both Buffett and Bachman are advocating policies that would hurt them. Rather than representing hypocrisy, this shows that they place a higher priority on the policies they find best than on their own wealth. In other words, they are putting principle over profits.
Hypocrisy might be if Buffett said we need higher taxes, just not on Buffett. Or if Bachman said we need to cut government, but not cut payments to health clinics.
Real hypocrisy would be if Buffett said, "all Americans should pay more than their tax bill," but he didn't. Or if Bachman said, "all Americans should reject all federal money," but she didn't.
Benefitting from something and advocating its abolition isn't hypocrisy. It's principle.