Lu Pi's rule is named after Lu Pi, who worked at the infamously corrupt Enron but cashed out before everything went to hell. At the time the film The Smartest Guys in The Room was made, he was not dead like Cliff Baxter (or, now, Ken Lay) or in jail like Jeff Skilling. He was the second-largest landowner in Colorado. Lu Pi has not cured cancer or come up with a Grand Unified Theory for Physics, or even figured out a way to make software suck less, but it's safe to say he's smarter than the titular Smartest Guys In The Room.
So Lu Pi's rule is: If you're the smartest guy in the room, in all likelihood it's because the smarter people have already left.