Asians spend twice as much time on homework as compared to Whites, and about three times as compared to Blacks. Kids of high income families spend more time working on homework than low income kids. So the fact that Asians comprise the student body proportionally larger than Whites, and whites more than Blacks is evidence that hard work pays off.
I think these claims that meritocracy is false lack nuance. It's not that meritocracy isn't fair, it's that a pure meritocracy free of bias is too fair: it doesn't attempt to rectify the fact not everyone starts with the same resources and that certain groups have different attitudes towards thinks like education than others.
Granted many of you are probably thinking that the fact that meritocracy doesn't correct for these things makes it inherently unfair, and many are probably thinking that the notion that our processes to allocate opportunitiea should correct for things like disparate time spent on study is itself an act of unfairness. And there's no one right answer to this. This is a kind of question where there is no answer, but rather society continuously develops and evolves a concensus about the right approach.