Rav Wolbe (Shiurei Chumash) comments that the mitzvah to study Torah is one that is incumbent upon each and every individual, no different than davening. Just as if someone else davens it does not exempt me from my personal obligation, I would have thought that also his Torah study cannot be accrued to my account. However, the Torah tells us otherwise. If one provides the financial backing so that his friend can learn Torah, he is a partner in all the Torah which is learned!
We find a similar idea in the Gemara (Meseches Kiddushin 29b). The Gemara asks what one should do if he has the ability to provide for either himself or his son to learn, but not both of them. Should he go to learn Torah or should he send his son in his place? The Gemara answers that if his son is more intellectually proficient, he should send his son. How will the father fulfill his own obligation to learn Torah? By sending his son in his place thereby enabling him to learn Torah, the Torah study will be accredited to both of them.
If one has the ability to learn, he doesn't have to rely on others to fulfill his obligation. However, if he is unable to learn full time, he can still get much Torah study accredited to his account if he supports those who spend their days and nights studying Torah.