I'd argue they are far from some of the smartest people in the world. Smart? Sure, some (many?) but I've known quite a few idiots in software. But I'd hardly compare the regular software engineer at a FAANG to some of the geniuses in the world.
But they put up with it because it's a career and not a job. Many of them couldn't handle a minimum wage or working class job. No breaks, short lunches, no wriggle room for life, permanent fast-tracks to firing.
I dunno, I would say on my whole in my 10 years at Google I really did meet some of the most talented (in terms of raw knowledge or focus or some other skill) people ever in my career.
But they were mostly being paid handsomely to apply those amazing skills to really humdrum tasks -- but painting them up to be really profound -- and that's the saddest thing.
But they put up with it because it's a career and not a job. Many of them couldn't handle a minimum wage or working class job. No breaks, short lunches, no wriggle room for life, permanent fast-tracks to firing.