Self-hosting FOSS over managed services is still somewhat a touchy topic. There is a lot of subtle FUD and FOMO out there that paint pictures of maintenance headaches and self-hosting risks. This isn't true. Many battle tested FOSS like Postgres are highly underrated for their resilience and easy of maintenance. Self-hosting gives total control, liberty over an organisation's technology stack in addition to deep expertise which in itself can become an organisation's moat. Cost savings from self-hosting can be so significant that they can represent two digit percentages of a company's bottom line, which can often mean life-and-death for up and coming startups. In this talk, I explore the idea of self-hosting FOSS from first principles using evidence from our work at Zerodha, where self-hosting FOSS gives our tiny tech team the agility and capability to operate systems at scale in addition to contributing significantly to our profitability. Postgres in particular, which we have creatively abused and perhaps stretched to some of its limits for handling massive amounts of critical financial data.