California's billionaires are spending about 1% of their tax exposure to kill Proposition 40

Building a Better California, the committee formed this year to defeat Proposition 40, has collected fresh money from venture and crypto principals: $7.5 million from John Doerr and $10 million from Chris Larsen, according to an August 14 campaign finance filing reported by the Financial Times ^[1][3]. Proposition 40 would impose a one-time 5% tax on the assets of California residents worth more than $1 billion, with the proceeds directed to state healthcare funding ^[2]. That is the point worth sitting with: a tax on unrealised net worth is no longer a thought experiment for California principals, it is a budget line.

Look at the arithmetic from the donors' side. Forbes puts Doerr at about $22.6 billion and Larsen at $11.4 billion ^[4]. A one-time 5% levy on those figures implies roughly $1.13 billion and $570 million respectively ^[1][2]. Doerr's contribution is about 0.66% of his implied liability; Larsen's is about 1.75% ^[3][4]. Forbes net worth is a crude proxy for a California asset base, so treat the ratios as indicative rather than exact. Even so, the expected-value case for writing the cheque does not require a high probability of changing the outcome.

The disclosed round also includes $946,000 from Lookout co-founder John Hering and $250,000 from Greenoaks Capital founder Neil Mehta ^[5], bringing those four contributions to about $18.7 million ^[5]. The committee reported an endowment of $110 million as of late June ^[6], and the New York Times reported last month that it has reserved $87 million of advertising time ahead of the November vote ^[7] - roughly 79% of the June total committed to air ^[6]. Sergey Brin, who moved many of his assets out of California late last year, has put $102 million toward opposing the tax, including a $20 million contribution to the committee this month ^[15].

The spending is not buying a comfortable position. A UC Berkeley Institute of Governmental Studies survey of more than 4,000 registered voters found 48% of likely voters in support and 41% opposed ^[8], a seven-point gap ^[7]. Democrats back it heavily, 80% of Republicans do not, and unaffiliated voters split evenly at 50% ^[9]. Institute co-director Eric Schickler said the contest is shaping up to be closely fought, with the question being whether opponents can make inroads among traditionally Democratic-leaning voters ^[10]. Governor Gavin Newsom and Democratic gubernatorial candidate Xavier Becerra oppose the measure, but the California Democratic Party endorsed it this month ^[14].

The committee's second front is structural rather than persuasive. It is backing Proposition 41, requiring state auditor review of special tax proposals, and Proposition 42, banning new taxes based on mere ownership of assets; either would cancel out the billionaire tax if it draws more votes, even if Proposition 40 also passes ^[11][12]. Awareness is the weak link: 72% of voters had heard of the billionaire tax, while fewer than a third knew the counter-initiatives exist ^[13]. Mark Cuban, who opposes the measure, wrote on X that if it passes, "only idiot startup founders stay in Cali" ^[16].

Watch three things into November. Whether awareness of Propositions 41 and 42 moves once the $87 million in reserved advertising runs ^[7][13]; whether unaffiliated support erodes from 50% ^[9]; and whether more principals follow Brin in relocating assets before the vote rather than after ^[15].