Why did the founders of Judaism start the religion?

No one actually started the religion. It began after Avraham figured out that there is One God; and later, when the Israelites stood as a nation at Mount Sinai and God had them receive the Torah.

Answer 2:

The founders of Judaism started their religion because of their encounter with God at Mt. Sinai.

Judaism is an offshoot of the Hebrew belief that occurred at Mt. Sinai. Much of the Jewish practices, rituals and beliefs focus more on traditions of man rather than the performance of the Law.

Answer 3:

The Hebrews are a people that were introduced to the ONE TRUE GOD, YHWH through the covenant relationship that God had with their great-grandfather Abraham.