No. The average person is, by definition, average. If mediocre opportunists didn't fill the ranks of nearly every outfit in America, they'd all be unemployed.
Typically if smart people have difficulty finding or keeping a job, it's either because a.) they don't want one or b.) they have mental or emotional problems that make them difficult to work with. The latter is a real problem, but not really an injustice (or rather, it's an injustice that people are born with or develop these problems, but not that they aren't hired if they have them). In that case, one's mental energy is often better spent dealing with those problems or enlisting help to deal with those problems than on becoming smarter, because you get a much higher payoff from the former.
True, but I'd then make the usual counterpoint that average is not the median or mode and can be misleading in its own way - the average human has half a vagina and <1 ball and <1 breast, the average human has <4 limbs and <2 eyes, etc
The average person can be quite feckless, even if you live in a population split between preternaturally intelligent clones of John von Neumann and people tragically in a coma...
The brain trust in most companies doesn't fill a beer boot.