On a Friday night in late January, the leader of a famed San Francisco venture capital firm got drunk and launched into a profanity-laced tirade on social media. Garry Tan, the Y Combinator CEO currently spearheading a tech-funded campaign to seize control of the city’s government, spent his long, strange night being publicly aggrieved by his usual foes: the progressive politicians he blames for the city’s ills.