the ability to become a tzaddik is a gift from G-d, not granted to every man. “You have created tzaddikim” thus means that G-d created souls capable of attaining the rank of tzaddik. Even if a person is not privileged to become a tzaddik, he should at the very least not be a rasha, being instead a beinoni.

By reason of the freedom of choice granted him, one is expected to surmount even the difficulty of faithfully observing this most difficult mitzvah of constant Torah study.

For this reason, the oath is administered a second time. Even if one does not have the opportunity to become a tzaddik, it is still possible for him—and therefore expected of him—not to be a rasha.