Deciding "worthless" is up to the person paying them. I may have an opinion of what my job is worth, but my employer has a much larger view of that worth than I'm privy to; if he's willing to pay me $X, then (perhaps to my bewilderment) my productivity is worth $X.
Sure, there are stark anecdotes, but on the whole the aphorism applies: a thing is worth only and exactly what another will give for it.
Sure, there are stark anecdotes, but on the whole the aphorism applies: a thing is worth only and exactly what another will give for it.