What is a fulfilling and prospective field/carrer?

I thought being compsci major and being a programmer making nice money is the end goal, but lately now that I'm living the dream and made enough money from markets, I'm really feeling a huge void. The things I'm working on aren't going to change anyone's life, most jobs are equally meaningless anyway and I want to start studying again and go somewhere where I can make a difference now that I have the money to live freely for next 30 years.

Any ideas? I feel like medicine is something that would make me happy, helping people, but it also has to do with programming/math that will capture my mind and make me work hard for next 15 years at least with a good goal and purpose in life.

Also it doesn't have to do with medicine, just give me some tips.