Recently taking a pen-testing course made me realize that security is such an important topic in software design, more so than I ever realized. Being a professional programmer for the last 15 years and attaining both undergraduate and graduate degrees in computer science helped me find only the basics of security. It took getting into the weeds to realize the woes of security flaws and in some cases these flaws are added on purpose (a feature request, where buggy code gets quickly added) to solve a problem and in turn end up adding a security risk. I guess in that case the feature was more important than the potential security risk.