Open source just means that the general public can view and reuse a software's code. Many developers contribute to open-source projects for fun, to build tools for themselves, or simply to gain experience. Additionally, many for-profit companies release "community" versions of their software to reduce development overhead while a small in-house team maintains a "premium" version of their software with enterprise features, managed hosting, and other niceties for non-technical users. In my case, I host and manage a stack of mostly open-source software to handle database design, website hosting / deployment, automation pipelines, API testing, customer relations management, document e-signatures, email building, and content management. This keeps my overhead low, allows me to undercut my competitors, and keeps your data safe and secure from malicious actors. That said, when it comes to handling sensitive data like accounting or payment details, rest assured I let paid 3rd-party services take on that liability.