The idea that there is a direct (and intrinsically necessary) correlation between hard work and wealth is a feel-good lie that those who have acquired wealth (sometimes, indeed, by hard work and talent, but more often by inheritance, luck, advantageous connections or chicanery) like to espouse in order to justify and perpetuate their frequently undeserved privilege.
Americans have long been duped, and it is well past time that we stop believing that the rich have necessarily "earned" their "superiority" because they have "worked harder." We do NOT live in that kind of idealistic meritocracy, despite the Horatio Alger myth that equates wealth with social worth and both with the compensation for hard (and especially, time-consuming) work. While more work--either in quantity or quality-- may indeed sometimes beget wealth, we have ample evidence that such effort often does little more than stave off poverty (if that).
No, the surest path to greater wealth is to already HAVE wealth, to be a Walton or a Hilton or a Kennedy. As a general rule, wealth is a pre-existing condition. Only rarely, by virtue of a lucky (i.e., random) confluence of talent and favorable circumstances, can we succeed in "working our way" out of inherited economic inferiority. Alas, the sad truth is that, for most of us, the only thing incontestably guaranteed by hard work is fatigue!