I've used so much open source code in projects over the last 10 years. We used to write everything ourselves. I'm feeling guilty now remembering some of the issues I've posted on open source GitHub. As a modern developer you just can't write everything from scratch. I'm thinking specifically now of React and all the open source built on top of it. React does and upgrade and a waterfall-like dance begins among all the components and routers used to augment it. Lots of work to sort through all the new code. It's free but there is a cost.