I've worked at a handful of FAANG companies in the Bay Area and Canada, and I have numerous close friends working at early to mid stage startups in San Francisco. Anecdotally, those at startups earn ~20-30% less cash and dramatically less total compensation if you consider the expected value of their equity packages. By my rough math, you really need to be employee <= 10 and exit at over $1B for the TC to surpass what a typical senior engineer can earn with far less risk at BigCo.