Google cofounder Sergey Brin has poured $82 million into an effort to undercut California's proposed billionaire tax. He isn't alone in the fight.

Google cofounder Sergey Brin has poured $82 million into an effort to undercut California's proposed billionaire tax. He isn't alone in the fight.

Sergey Brin has spent $82m fighting California's 5% billionaire tax, leading a tech-elite campaign that outspends the measure's union backers 4 to 1.