Torah Sustains the World
Torah learning
Rav Elchonon was once asked why learning Torah is considered more important than all other mitzvos, and what good he does for another person by studying Torah. He answered that if Jews stopped learning Torah, the world would go under, because its existence depends on Jews learning. A Jew who learns Torah therefore has the mitzvah, and more than that, he sustains the entire world and prevents its destruction.
Source: A Fire in His Soul: Irving M. Bunim