Do you believe the Bible to be inspired? If so, is it because there are certain scriptures that declare the Bible to be inspired. Why would you believe those scriptures to be inspired? Because they are in the Bible? If you were to say yes to the last part, then that would be circular reasoning, which would prove nothing.
You have faith in sola scriptura, and other Christians have faith in the scriptures along with the Oral Tradition.
Oral Tradition can be boiled down to circular reasoning, too. So you have your faith and they have their faith, but in the end, “Without faith it is impossible to please God, for they that come to God must believe [by faith] that He exists and that he is a rewarder of them that diligently seek him."