1)
Why did he go to the Gedolim?
1.
Rashi: He thought that they would heed him. However, they cast Hashem's yoke off of them.
2.
Radak: Since they are rich, and do not engage in work, they have time to learn Torah and Chachmah. Most are Ba'alei Musar and Da'as, and learned Torah and Mishpat of their G-d. Perhaps my rebuke will help, for they will understand.
3.
Malbim: They know that the punishment is Hashgachah, for the sin.
2)
Why does it say "Shavru Ol"?
1.
Malbim: They view Torah and Mitzvos as a yoke on them. They broke it and cast it off; they recognize their Master and intend to rebel against Him.
