The problem with overly progressive taxation:

Nearly half of California's income taxes before the recession came from the top 1% of earners: households that took in more than $490,000 a year. High earners, it turns out, have especially volatile incomes--their earnings fell by more than twice as much as the rest of the population's during the recession. When they crashed, they took California's finances down with them.

Mr. Williams, a former economic forecaster for the state, spent more than a decade warning state leaders about California's over-dependence on the rich. "We created a revenue cliff," he said. "We built a large part of our government on the state's most unstable income group."