I knew a Cadet who was listed as schizophrenic in his files, and he was without question the brightest, most dedicated LET 1 (entry level) Cadet under my command. He was an eye opener for me.
Unfortunately, as said, the only time most people ever hear about schizophrenia is when it's reported over the news or featured in some movie. Ignorance fosters ignorance.
Don't let them get you down. Next time they bring it up, point out the schizophrenic in your group of friends is the only one smart enough to not speak about what isn't understood.