It's also true that even a "mediocre" engineer is elite in many ways - they are "mediocre" compared to all the other folks who managed to carve out a sustained engineering career. However, even somebody in the middle of that group has elite engineering skill relative to the population at large.

This is true of many careers, of course!

I always feel bad for the professional athletes who "suck." It's kind of hilarious -- even the "worst" professional athlete in a given professional sports league is actually an extremely elite specimen, with only a tiny fraction of all athletes even being able to make it into such a league.