Positing that hard work guarantees anything is the lie. It is a narrative that has been perpetuated by all those who benefit by exploiting hard work.
Smart work ought to be more beneficial than hard work but the narrative focuses on “hard work” with connotations of pushing oneself beyond one’s comfort zone and limits, which implies increased exploit-ability.
It is an immoral statement which left without investigation causes suffering and inequality for many.
Hard work depletes the worker and is therefore ineffective as it creates an imbalance which that person, their family etc. need to pick up. This balance is not reflected by the accounting of the employer so economically it is hard to detect.