As opiura said, no one will ever use everything you are exposed to in school, but by being exposed to a lot of different subjects and ideas, it helps you decide what you are interested in doing for a living. My son is going through that right now. He graduated from HS this year and not sure what he wants to do. He graduated with high honors but currently has no desire to go to college. He is still young and will figure it out. He is already getting a taste of what it's like to have to work for a living and he is working very hard for very little right now.
I have an Engineering degree so my degree was heavy in Math and Science. Calc 1, 2 and 3, Chemistry 1 and 2, Physics 1 and 2, Statics, Thermodynamics and the list goes on and on. It's funny but I couldn't sit down and do this out of my head now to save my life. It's been too long and I don't use it in my everyday work and never will. I'm a Technical Architect and I design Information Technology Solutions for a 10 billion dollar company. When they need to turn out a new solution for our customers, I architect the solution to include software used, servers, operating systems, databases, web servers, security, network layout, DMZs, WAN connection to other sites, protocols and everything that will be needed end to end to meet the business requirements. I diagram it out, document it, sign off on it and hand it off for someone to build and put it out there.
My main point is I spent 5 years in Engineering school learning tons of information that I have never used, but needed to get that piece of paper that allows me to do what I do today. It's the same for highschool. It's just something you have to accept as necessary. It's not always fun but man is it so worth it when you get through it all.