California's Billionaire-Drain

California's Proposition 40, a one-time wealth tax of resident billionaires is on the ballot. Economists and conservative media outlets argue, correctly that this is a terrible idea from the standpoint of the government increasing its tax revenue. (We'll set aside our disappointment that none express any degree of moral outrage at this brazen violation of individual rights.)Megan McArdle takes this line of argument further, considering what dueling economists are saying about the potential impact of such a measure -- and assuming in order to make their cases.In addition to questioning assumptions about what the billionaires might do in response to such a measure, she considers what this "group of the world's most mobile people" are doing:Several California billionaires have already announced their departures, including Peter Thiel and Google founders Larry Page and Sergey Brin. [Wealth tax proponent Gabriel] Zucman's paper notes that if some of the most prominent tech barons succeed…