YC pioneered the modern batch-based accelerator model in 2005, systematically transforming tiny MVPs into venture-scale companies at industrial scale with 400+ startups per batch and a portfolio exceeding 4,000 companies, achieving unusually high success rates where ~4.5-5.5% become unicorns compared to ~2.5% for other venture-backed startups. The program functions as a "brutal" peer-pressure learning environment where ~200 founders rapidly stress-test each other's ideas while Jessica Livingston serves as the fund's "social radar" to screen for founder character and create a psychologically safe, founder-first culture—positioning YC as career-risk infrastructure that makes starting a startup less risky for talented people rather than just a capital provider.