I actually feel pretty good about most of what I learned in high school, to be honest. I like learning, I like knowing things. I think there's value in every academic subject.
Do I use it all in my current daily life? Of course not. But I think it's worthwhile to have studied literature from all over the world, and to have studied history. It gives me a broader perspective on the various cultures and ideologies that drive people today. I think it's worthwhile to have studied economics and government and art. And obviously as an engineer, I value the science and math I learned. Even subjects like biology, that have never directly impacted my professional career, have value in helping understand how the world around us works.