Sure it is. Hard work weights probability in your favour and gives you more opportunities. Surely that's the best anyone can ever hope for? Do you have a system in mind that makes guarantees?
A meritocracy isn't about guarantees, other than ranking is by performance not externalities. By most definitions, a meritocracy is impractical, granted. In a real-world sense, the socio-economic status of every individual on earth is primarily governed by luck/circumstance. Not to say there aren't exceptions, but there has to be an inordinate amount of "merit" AND luck to overcome the initial state, statistically. To whit, a human lifetime is more complex and complicated to navigate, than the 3 body problem.