@CS Almost all of the Chachamim learned things from secular people. The Tana’im talk about Aristotle. Tosfos quotes Socrates. The Gra hired tutors for almost every subject studied at the time.
I question your interpretation of “secular studies are metamei the brain”. Perhaps when the previous previous Lubavitcher Rebbe ZT”L said that, he meant studying useless goyish things, like Indian mythology or comparative literature, and not the type of studies that can help a person understand the world (which are absolutely not “secular” no matter what your Cheder called them).