Why is Mark Zuckerberg spending millions to back harmful Proposition 15?

The other day, we read with open-mouths that the world’s fourth richest person, Mark Zuckerberg, made another contribution to the Yes on Proposition 15 campaign, bringing his total contributions to more than $10.5 million.
In publicly highlighting the campaign contribution, the Facebook founder made a conscious effort to point out – erroneously – that Prop. 15 was “designed to generate and stabilize funding for vulnerable communities…and would put fu