One other thing I forgot to mention is that the ultra-wealthy typically earn most of their money from investments, not income. This is why Mitt Romney pays a net lower tax rate than you or I and another reason why even progressive income taxes are fairly regressive.
State taxes often treat investment and wage income the same; particularly in California.
Formerly 15% + 0% (if you lived in WA) capital gains one year is now 20% + 3.8% + 14.3% (if you moved to California in 2013). That's a pretty big difference for the same gain.
