Trying hard or trying to be smart are no substitute for doing it right. You have to play correctly/competently.
A chess player who tries their best with brute force by working hard/long hours on learning the game through practice will not necessarily going to be a grand master.
A chess player who has the most intelligence about the game will not necessarily become a grand master.
A chess player who executes the optimal strategies with consistency is a more likely candidate to become a grand master.