Why? Just because you work hard doesn't mean you deserve more
Its a major element of the ideology associated with the Protestant work ethic, which has an important role in American culture -- and ties intimately into the way large parts of the more successful population can dismiss the less successful as being so as a result of choice and moral failing -- that hard work both does, in fact, and should, in moral ideal, result in material success.
Even lots of people who intellectually reject the position are have been to some degree socialized in it and feel some dissonance when contrary facts are particularly palpable.
I'd say your claim is nonobvious. That the world is fundamentally fair, and that hard work is the most important aspect of virtue, are deep ideas in American culture and very much tied up with the American Dream (TM).
Contemporary liberals typically challenge the "world is fundamentally fair" part, appealing to structural *-ism that makes this untrue for people other than white men born to financially secure parents.
Few (economists, maybe) would argue that how hard you work does not influence how much you deserve.
(Ironically, people pay to lift weights at the gym, they don't get paid to! It's pretty darned hard work, too.)
I put together a few lines today that automates a 5-minute process. Across the scope of a few thousand servers, this obviates about 6.25 weeks of labor. It really does feel magical.