One of the all-time smartest people I’ve ever met worked a bar in Bergen, Norway; autodidact in anything which caught his fancy, he could give you a lecture on what brought down the Scythians, serve a new guest and striking up a conversation on advances in semiconductor fabrication with him, picking up where he left off the lecture on the Scythians before heading out to see if any of the patrons outside wanted anything, having a quick word on the Poincaré conjecture with the math postgrad having a beer in the backyard...
He had studied for a while at the university before figuring out that he’d have more time to study if he didn’t have to concern himself with exams, quit, kept his uni library card and got down to it.