California voters will decide on Proposition 40, a ballot measure that would create a one-time 5% tax on the wealth of the state’s billionaires. The vote is scheduled for November 3. If approved,. Google co-founder Sergey Brin with his girlfriend, Gerelyn Gilbert-Soto. Brin, whose net worth is estimated at nearly $260 billion, would be among the biggest taxpayers affected if the proposed.