Making the wrong choice on build vs buy

The author reflects on a past decision to build an expenses software instead of purchasing one, highlighting several mistakes made during this process. They underestimated the complexity of the task and found it increasingly difficult to maintain as time went on. Additionally, they failed to consider the opportunity cost of building an internal system rather than focusing on their company's core product. The author also mentions that leaving a legacy behind after departing from the company made maintenance even more challenging. They conclude by discussing when it is appropriate to build something in-house and emphasize the importance of considering the value of one's time before making such decisions.