Understanding Bitcoin, let alone understanding how to build on or with it, is no easy task. But Adam Ficsor shares some of the lessons he's learned and mental models he's built throughout the process of leading Wasabi development at Blockstream. Accepting the nuanced nature and sometimes misnomer labels of many features and facets of Bitcoin's protocol is important to building well. Understanding the responsibility developers shoulder, moreover, to build reliably secure products begins by understanding when things should and should not change in the given version of a protocol or piece of software.