2 Timothy 3 does not say "sufficient". It says, "profitable" or "useful". The goal is to have the "man of God" perfected, and the scripture is useful for that goal. No one argues otherwise, the scripture is extremely useful.
What else us useful? Why tradition is, that which St. Paul taught Timothy orally (2 Tim. 1:13, 2:2). In fact, St. Paul made a reference to the tradition first in 3:14, and after that he turned his attention to the scripture in verses 15 and following.
It says, “16 All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness, 17that the man of God may be competent, equipped for every good work.”
Scripture is breathed by God, and useful to teach, reprove, correct and train so that “the man of God may be competent (”having suitable or sufficient skill, knowledge, experience, etc., for some purpose; properly qualified), equipped for every good work.”
Or as the NIV translates it, “16 All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness, 17 so that the man of God may be thoroughly equipped for every good work.”
What is it ‘useful’ for? Teaching and training so that a man may be fully equipped for every good work. Thoroughly equipped seems the best translation, but even adequately equipped (all that is needed) for every good work, not just some.
Verse 14 doesn’t set up “tradition”, but says, “14 But as for you, continue in what you have learned and have become convinced of, because you know those from whom you learned it.”
Now if you have traditions handed down from the Apostles, fine. Timothy knew them and was taught by them orally. Indeed, they then WROTE most of the NT! However, what Catholic tradition came from the Apostles? Purgatory? Not hardly. Indulgences? Not hardly. Primacy of the Pope? Not hardly.
Those innovations came about hundreds of years later. Transubstantiation took nearly 1000 years.
If you have some tradition from Peter or Paul, I’m all ears...and that is a metaphor. But traditions from a medieval monk? No thanks - not unless those traditions align with scripture.